1640 lift arms went up but won’t come down

Hi all,
Just reassembled my 1640 after removing the rockshaft cover to get at the hand brake and when tested the lift arms went up, like waaaay up and now won’t come back down. Is there a lever or something that I haven’t lined up properly when lowering the rockshaft cover back down? All was working well before disassembly
Thanks for any help!
 

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Try opening rate of drop screw located under the operators seat. Another possibility is you didn't position cam follower(shaded part) into 3pt control linkage correctly.
 

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Try opening rate of drop screw located under the operators seat. Another possibility is you didn't position cam follower(shaded part) into 3pt control linkage correctly.
Thanks Tx Jim, tried that and still won’t go down and yes I believe I mucked up when lowering the cover back down. Have it off again now and lift arms are still locked right up and can’t get them to budge at all. Can I undo one of the nuts on the back of the lift arm cylinder to dump any oil out of there?
 
Thanks Tx Jim, tried that and still won’t go down and yes I believe I mucked up when lowering the cover back down. Have it off again now and lift arms are still locked right up and can’t get them to budge at all. Can I undo one of the nuts on the back of the lift arm cylinder to dump any oil out of there?
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You're welcome
Leaving rate of drop screw unseated (CCW) I suggest to push 3pt control linkage(item 16) that has a roller forward while 3 pt control handle is pushed forward/down.
 

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It doesn't look too high...If screw has unseated it shouldn't matter which way lever is positioned ours it unseats itself from time to time you have to remember to tighten it back up. But Tx Jim has a good idea try both. Sometimes they can get stuck as well if not used often. I assume you have hung at least 250 lbs of weight off each arm at the same time? We have had to put the skidloader on larger tractors that don't have that nice screw if its super cold out to get them to drop.

If it hadn't been raising all the way up recently it is entirely possible it has been in an area of the cylinder that hasn't been used for awhile and might be binding a bit.

If you have it off a large pry bar in the fat machined area of the case not far from where your bolt holding the strap is on the end of that lever the cylinder rod is pushing on I couldn't get the 2nd screenshot of Jims to load clear so if you can't see the numbers that should be where to push they should if lifted up flop back down with very little resistance
 
You're welcome
Leaving rate of drop screw unseated (CCW) I suggest to push 3pt control linkage(item 16) that has a roller forward while 3 pt control handle is pushed forward/down.
Thanks Tx Jim it worked! Will update when all reassembled. This tractor is special to me as it was the tractor I learnt to operate farm machinery on my first job on a dairy farm after leaving school at 17. By a stroke of luck and now aged 41 I now own it so was hoping I hadn’t damaged it!
Thanks again mate :)
 
Thanks mate, about to lower the rockshaft cover back on and I found this washer in the alloy reservoir, any idea where that may have come from
You're welcome
I seriously doubt you have damaged RS control system beyond repair.
Also just found this bolt unwound and missing the nut, do you by chance have access to an exploded view diagram with part numbers?
Thanks for your help thus far mate it is
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most appreciated!
 

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JDparts.com is only exploded view that I would have access to. Have you considered acquiring a 1640 tech manual? I'll suggest to reattach loose end of the spring before resetting RS housing onto trans case. https://partscatalog.deere.com/jdrc/sidebyside/equipment/7072/referrer/navigation/pgId/1394731
Tx Jim
Thanks so much for your help thus far however I now have another issue! I have the lift arms working as they should but when they are lowered as far down as they can go the engine loads up as if the hydraulic system is at full pressure and relieving. Also when they are lifted in any position I am able to push them down by hand and the system loads up. Could this be air in the system after putting everything back together? I did my best to bleed every line I removed but maybe I missed something? Thanks again for your help!
 
Sounds as if rockshaft control valve seals are leaking or the valve clearances are set too tight. With 3pt raised, hyd oil at operating temp, engine operating at idle look inside hyd fill hole behind seat for moving oil indicating the problem. One should adjust valves & control linkages following instructions in JD tech manual.
 

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