620 Power Steering, clutch, gear shift

Making progress on the 620 I recently bought. Changing fluids, new quick couplers to replace leakers etc.

Power steering: When turning fast it would lock up when I try to turn back straight. I changed the fluid and replaced with John Deere two cylinder oil (book says it should hold 5 qt. but only took a bit over 3). When I pulled the drain plug nothing came out until I opened the dipstick. It looks like there should be a vent in the top of the dipstick cap but I sure can't find one. I scraped all over the small circle in the top of the cap with a small nail but nothing there. When I leave the dipstick loose now it doesn't lock up but when I tighten the cap by hand it will lock on a fast turn until I stop trying to straighten it out. Should I drill a hole in the cap? Am I looking in the wrong place for the vent hole? There are two holes in the dipstick near the top.

Clutch has a good snap but when you pull it back the tractor keeps moving unless I hit the brakes or pull the clutch way back. Doesn't try to move then. I tried loosening the clutch but that didn't change it. The belt pulley doesn't seem to be binding when I rotate it by hand when the clutch is released. The brake pad is shot and a new one will be here Tuesday. Plan to adjust the pulley brake as per the manual after I get the new pad. Maybe that will take care on it?

When I move the shift from the right quadrant to the left, if the clutch pulley rotates at all it stays in neutral when shifting into left quadrant gears. Move the shift back to the right quadrant and then back left with the clutch pulley stopped and all is well. Can't remember any of the 520 to 730s I've owned doing this.

Thanks in advance for any help. Trying to get it ready for plow day on the 19th.

The vent is a sintered bronze bushing in the center. It is possibly plugged up.

You might try soaking the vent end of the dip stick in laquer thinner.

The clutch brake could be your problem because if the clutch lever is allowed to travel too far back the clutch can start to re-engage.

The shifter forks are probably worn which is not allowing the low range gears to fully mesh together. I'd try adjusting the shifter forks to start with. It's kinda hard to explain how to adjust the forks so I'd suggest getting a manual for a model 60 which is SM2008. Deere didn't make one specifically for the 620.

Is something that needs attention before it's worked hard - as in plow day next Sunday? If the low side gears aren't fully meshed that can't be good.

In that case 3rd gear will be your safest bet since it's on the high range side