Allis FWD 8050 Powershift Issues

Got a good one for you guys. Tractor quit moving so the powershift was pulled and hauled into the local dealer for a "rebuild". Got it back and installed it in the tractor. Worked for 5 hours then quit again. Dealer wouldn't warranty because they just got the powershift and not the whole tractor so we decided to split it. Found that there was multiple piston seals ripped. Replaced all the seals and reinstalled in the transmission. Its been working for over 50 hours now however its developed a random problem. It will be driving and happens in any range or powershift. It acts like someone shifted the transmission into neutral and it just coasts to a stop. The range and powershift were not moved nor the clutch pressed it will be driving just fine and then coast to a stop. If i mess with the range/powershift it will start going again. Sometimes its 5 minuets and sometimes its 45 minuets. Removed range transmission cover and when it acts up all the range gears stop turning but you can still hear the hum of the clutch drums turning so I'm convinced its in the powershift somewhere. Also when it acts up the steering, brakes, and pto all still work just wont move. All clutch pressures are perfect to spec when it acts up as well. Any ideas are greatly appreciated.  

Sorry for the late reply I'm not very tech savvy. Checked pressure at all 1/8" pipe plugs for the a,b,c,d clutch's and when the tractor stops moving. Each clutch pressure does not drop. Stays good at 210psi which according to the manual is the correct pressure. Doesn't matter if the oil is cold or hot the result is still random. When the tractor stops moving with the range cover off of the top of the transmission. The gears stop turning but i can hear the hum of the powershift clutch packs still turning. It seems like there is a disconnect from the range transmission to the powershift. When i seen it split it looks like there was only a collar connecting the two but the splines were in great shape and there is no grinding noise at all when its driving or stopped. When i shift the powershift gears i can hear it shift in the powershift. rpm light on the dash works and does go out when required. Powershift valve was gone through and also replaced as the dealer had the parts cannon out .   

This may be out of left field. Just thinking of anything that might help. It semms to me the inching valve is dumping pressure on the clutches causing the tractor to stop. Sinc you have had it apart i think id go through the procedure to adjust the inching valve to factory spec. That thing is sensitve and it doesnt take much to throw it off. You may have slready done that i dont know. Trying to think of anything to keep you from having to split it again

Ok i also agree that it seems the powershift is working but i find it weird how the coupler could come undone and then slide back on. I was wondering what connects the input shaft from the engine to the range transmission. Does it go flywheel clutch pack then output shaft of powershift, then coupler, then range. Like what's the path of power maybe that'll help pinpoint this. I would like multigauge set like that but i only have a single gauge set as the multi is pricy.