John Deere 420 Starter Locking up

I have a 420 where the starter occasionally just locks up, i.e., trying to turn over the starter, nothing happens, just get a click. When I loosen the starter and work the housing back (have to take the battery box off to be able to remove the starter) and then re-attach the starter it will start cranking the engine again. At least that worked today; last time, took the starter off and then re-installed. I decided to just try moving the starter back out as far as I could today without removing the battery, battery box, and all.

This has been quite frustrating, tractor died on my son about a month ago while he was doing some work for me. Could not get it to restart. Have been trying to troubleshoot and then the starter starts acting up. Looks like I"m not getting spark. With the switch, I only get 3.5 volts at the coil, bypassing the switch as recommended here gets 6 volts to the coil but still no joy. Have replaced the coil, points, and condenser. No joy. It looks like I"m getting intermittent spark. Then, when I think I have something to try, the starter decides to stop spinning.
 
(quoted from post at 03:57:56 07/27/14) Put a new starter drive on my 430 and solved the problem

Thanks; I'll put that on the list. This tractor has decided to go south on me all at once. It's been pretty trouble free up until now. Now it's just piling things on.

Appreciate the answer.
 
Locked up starters generally only happen when the bushings at either end are so worn out that the armature makes contact with the field coils. At that moment the urge to turn is negated entirely by steel to steel contact and the intense friction created by that. A new bendix certainly won't hurt, but you'll miss the boat if you don't replace both bushings while you got it apart. A sure sign that you need bushing is a scraped armature and/or field pole pieces. A lot of starters meet their end when this situation continues on and on to the point both the armature and pole pieces can be seen to have been tempered blue from the ungodly friction and the winding insulation(s) burnt up and shorted out.

Chances are good your armature shaft bearing surfaces are undersized at this point so bushings to compensate would be a cheap fix for that. $20 dial micrometer could pay for itself on this job alone - custom sized brass bushings from McMaster Carr a very real possibility.
 
You might consider checking the switch on the starter.

It may not be making a good connection with the copper stud on the starter.

Remove the switch and touch the battery cable to the starter stud.

If the starter works and cranks the engine, then consider a new switch.

You might also consider taking the starter to a repair shop and have the copper stud rotated 180<sup>o</sup>.

It could be worn and not making good contact with the switch.

You might also make sure that the battery cables are clean and tight; especially the ground cable.

Know all to well about the fateful "click" and removing the battery box.

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In the past "Rusty", one of our MTs, would stop running as if the ignition switch had been turned off.

It has gone through condensers regularly; some new condensers last longer than others.

Hope this helps.
 
I have a 320 that starter locks up on now and then, usually I can put it in gear and rock it and it will release. Once when I couldn't get it to kick out by rocking I just listened the jam nut and allen screw and wiggled it a little. My 430 starter will lock up occasionally and I can't rock the tractor with loader on it. I losten the 2 starter nuts and wiggle it and it comes loose. The 320 has the battery box issue but still enough room to move the starter a little.
 
Thanks to all for your recommendations. After more work today, I confirmed that I am getting spark when I remove the ignition switch from the low negative side of the coil and connect directly to the battery terminal on the starter, so I'm pretty sure the ignition switch is what went bad when the tractor died.

However, now the starter is acting up sufficiently that I'm pretty sure that is why I can't get the tractor to start -- it can't spin fast enough and the bendix kicks out too soon if it does get close to starting. So next step is to get the starter rebuilt. Not sure yet whether to try having it rebuilt here in "never get it done right the first time Tucson" or go with an online vendor like tractorparts.com or All States Ag Parts. I'm leaning toward on-line and All States.

It's been a good tractor up to now. This past month, it has been very temperamental
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