Bobcat 632 little to no drive forwards or reverse

[Chris:1979 clark 632]

Hello and thank you in advance to everyone for all the great info and knowledge on this forum. I've been looking in from the outside occasionally but this is my first post. I have had this 1979 bobcat 632 for about 4 years. It's been a great little machine for me around here on my acreage .ive done a lot to it over the years. I'm a journeyman mechanic and an engine machinist . To get to the point , I'm having issues with the hydrostatic drive. I took both drive motors out to have tested . A friend of mine said he would put them on there test bench for free. Why not. I was originally overfilling the chain case with oil. One motor is a replacement and the other is oe. The oe one showed a fair bit of wear but they worked just fine. ( case drain was flowing more than allowable. My friend put new seals in both on shaft sides and reseller the oe one completely. Now once there back in it worked for about ten minutes perfectly. No noise no nothing. Then it stopped . Almost immediately. The oe motor side has next to no movement and the other has just enough for it to creep in the flat of my shop. Hydraulics all seam to work ok. I lifted it fully off the ground and the oe side you can stop by hand when the leaver is pulled. The other side is moving much better but still so weak. Ive pulled out the bronze filter and will replace it with a new one once I figure out the problem. Also changes the engine bay screw on filter . Just to be sure. I also pulled out and inspected all bypass and relief valves except the main pressure one. When it's on the ground the oe motor side almost makes no noise when I pull that stick and the other side wines really bad when I pull that stick an moves very little. Any advice or info would be greatly appreciated , wondering if somehow the bad wheel motor could be doing all of this? I've also seen a few posts I similar issues but no one gets back on I think here to post the repair . At least that I can see. Thank you all again , take care, Chris