Some times things are so simple

Thought my 2015 Jeep Grand Cherokee transmission had a problem. I would shift to Dr. the trans would just shift back into Park, reverse same thing. Almost ready to have it towed. Got to looking in the net. It has a safety feature if any door is open, it will not move. Closed the door works as advertised.
One time my crawler was making a terrible scraping noise. I thought it was a bad track roller. almost ready to tear into it, when I fond a rock stuck between the rock guard and a roller, making the noise. Ever do an unnecessary reapair? Stan

when chev first came out with safety devise that required you to step on the brake pedal to put in gear I rented a truck in Jackson hole wy. somehow I got it right at the airport pulled out on the highway then pulled over to take pictures jumped back in and you think I could figure why I could notit get back in gear, got out checked all the doors seatbelt then finally pushed hard enough on the pedal JEEZS

had a chevy that ran good but no power, did a lot of engine work, carb work....turned out to be the intermediate pipe was a double wall and the inside pipe had collapsed.

Many years ago I brought a 1969 Chevy pickup. I paid $100 for it. Guy told me it would run but not pull it self. So I set a battery in it and tried to fire it up. It fired right up but after a few minutes started choking down. I figured the choke was stuck closed. I started taking the top of the air cleaner off but as I did that it started to run better. I looked at the air filter and it was covered with dust and dirt. Threw it in the bad of the truck got in and drove off. Heard latter that the guy was still kicking him self every time he saw that truck driving around town. I still have parts and piece of it

Not a vehicle, but a CNC lathe.

Started doing strange things, garbled screen, shutting down in the middle of a program. Started out intermittent, but got worse to the point it was not usable.

I spent a week looking for problem, but very limited with no access to any schematics. Finally called the local dealer service. They spent 2 days searching, gave up and called Fanuc, the company that made the brain.

That is always a last resort as they are extremely expensive, charge by the minute from the time they leave until they get back to the shop, which can be hours away, even airline miles away.

The way they do it, send out the trainee, see if he can find it. Next send out someone more qualified, work their way up to someone that can finally find the problem. Lots of part swapping and guess work even for the best techs. You get charged the same per minute for all of them, fix of fail.

After a week of dealing with it shutting down, a week waiting for service, another week of paying for service...

The problem was a pinched wire that had fallen down out of place and was caught in the door!

Tore an engine apart on a ford compact tractor one time that another tech looked at and said it needed an overhaul so I overhauled it then found a loose delivery valve on the injection pump . Rebuilt a transmission one time wouldn?t stay in 5th found I had turned the shift collar over when I put it back together

That brings up about the same problem I had years ago, I forgot about. One of my crawlers started running real bad. I changed the carb, not the problem. Changed the mag same problem. I didn't think it was a plugged air cleaner, because I service it often. Checked the air cleaner it was full of little seeds. Live and learn. Stan

Now wouldn't that frost ya!! Amazing how on the old equipment we play around with if you just pull out an oil can and the stupid grease gun!!! Have found that out a couple of times.

I don?t feel near so bad about my engine overhaul now

Not a tractor or pickup, but a 10 wheel truck with an ISM Cummins. A new truck with excess crankcase pressure, put new rings in, then found out the road draft tube (rubber) was pinched over 180 degrees!!

S-10 Blazer,the starter locked up. It had the small V6,cross member and exhaust had to come out to get to the starter. rebuilt still would not turn it over,the alternator was locked up.

Coolant leak on the back of a 95 chevy 350. Replace the intake gasket. It was a ten dollar seal for the coolant line to the heater. Oh well.
I almost bought a new resistor for my 9n Ford. Took it a part instead and cleaned it up and it now works.
Too depressing to think of all of them.

Seen that on a lawn mower one time

Drove a Freightshaker with a Series 60 Detroit, I barely got to Kingman, AZ nearly out of oil, oil all over the bottom of the truck. Couldn't go to Granolaland like that with a load of meat. Truck ran great sitting still, drive it a little and it blew oil out the road draft pipe. Checked everything even did a compression check. Day and a half later finally found the air compressor had eaten one piston. Air compressor intakes from intake manafold. Drive it and turbo was pressureizing the crankcase, blowing oil everywhere. Turbo would not build boost setting still.

I've seen that only this car wouldn't start at all. They worked over everything. Once when they took the exhaust pipes off to check something else, the boss thought to hit the key. Started right up! Took weeks to solve it.

I bought an early '90s (as I recall) Tarus sedan. Electric windows. First time I hit the driver's window it went all the way down by itself. I tried to fix it and was nothing to fix.....later find out that it was designed that way and the reason. Oh well.

Neighbor had a mint 63 Impala it was his wife's pride and joy.
Shortly after installing a fresh built engine at an idle there was a faint knock coming from it.
After checking everything he could think of he pulled the engine and took it back to the machine shop that built it.
They went right through it, he put it back in and same knock.
Changed the fuel pump and knock was gone.

Bought a mid 80's Ford 1-ton dirt cheap as the seller said the engine was seized.
Started to take it apart, tried to bar over the engine to get to the converter bolts, one way and it would not budge, tried the other way and it moved followed by klink noise.
Turned out the drive gear from the starter had broke in two and a piece of it was wedged between the ring gear and bell housing.

A customer that I did maintenance for on a fleet of tow trucks called the shop one day and asked me to order in a starter for his truck, he was super busy that day and the starter on his was crapping out and just barely got his engine started.
A few hours later he pulled up at the shop door and honked his horn, we opened the door and he drove onto the hoist, swapped out the starter, he hopped in and turned the key, click, click, click I asked him if he wanted us to check his battery and charging system.
A few foul words from him later and he was on his way with a new battery (and starter).

Another customer paid to have his F 150 towed to the shop from 2 hours away when it arrived I showed him how to reset the inertia switch on his truck, he had backed up to a loading dock and set it off.

I bought an Allis 175 diesel that the seller had put a new engine in and claimed less than 100 hours on it. After a couple of weeks it started running rough and smoking. I took it to the local Perkins shop as I had no idea what to look for. I told them I had another injector pump if the one on it was bad. They decided to change out the pump. They called and told me it was running better...no pto dyno (they were a truck shop), so they were just driving it around. He told me that they disconnected the pre-heat gizmo as it was leaking fuel. Duh, that was the problem, it was dumping fuel into the intake...cost me $500 and 3 trips to town.

I had a 74 Nova SS that developed a knock after I went back to the farm for a weekend. Luckily I saw the stone wedged in the crankshaft pulley before I took it to a mechanic....dang gravel roads!