Bobcat 753 drive is jerking

[pjcat]

I recently purchased an older 753 serial# 508615824 The engine has only 1080h on it, but the machine was sitting for quiet a while. So I serviced everything, replaced hoses, the whole tlc. After all I tested the machine and it worked great, had to adjust the neutral a little and everything was fine.
Then on one of the drive motors oil started to leak; I found on one of the hoses the o-ring went bad. So I replaced it and the leak stopped. But now that motor is jerking in forward; I have to push the steering lever hard forward and back to get the motor going and then it feels like it slows down again, but it's only in forward a problem, reverse seems to work ok. I was thinking if there is air in the system that needs to be bleeded? But I couldn't find any info for something like that, so that's probably not the problem.
What could it be then, I only changed the o-ring and before it was working fine?
Thanks for any advice.
pj

 

[pjcat]

Anybody has some suggestion?
Thanks
pj

 

[pjcat]

By now I can answer this myself: Took out the motor and found pieces of the old o-ring were stuck in the directional check valve/relief. To make sure I opened up the whole thing and also saw that parts of the interior seals were totally deteriorated; they literally dissolved. So I ordered a new seal kit and got new o-rings; waiting for it to arrive and slam it back together, and call me an experience richer.
Thanks.
pj

 

[Tenwheeler]

Thanks I own one doing the same thing. Was told it needs a pump from an experienced owner operator. I am sure that would fix it but have been putting it off. Will check that out soon.

 

[pjcat]

I was surprised that just some small little pieces of an o-ring can jam it up like that.
On the other hand now after opening it I can say that theses motors are really not that complicated as I thought. I was looking at more difficult hydraulic components in the past. The only thing is important to reassemble it correctly back together.
pj