PTO hydraulic pressure

Last winter my new to me 656 was slipping the PTO on my IH 80 blower. A complete change of hyd oil and filter helped enough to finish the winter. My local independent shop dismantled the PTO and completely rebuilt the unit, using IH parts. The fiber discs were cooked and some steel ones were bad. All was replaced, and the hyd oil and filter chanced again after 27 hours. Putting a pressure guage on now, the pressure is 50 pounds at initial engagement, HOWEVER, ( I hate that word...)when fully engaged, the reading is 105 pounds. He air pressure checked the unit before installation looking for leaks and found none. In my former farming days, I did a lot on 656s thru 1086s and never had a pressure problem. I talked to two older ( in their 70s) good old IH mechanics and they could not recall a pressure pump problem, nor is the power steering or remotes an issue, and the rear and the pto were free from debris.Is there something we are missing, or am faced with a pump replacement. Is there a cheaper solution, can I just replace the pump gears, machine the tolerances... Every hour of experimentation is on the meter. Thank you for all suggestions.

Question, does the pressure decrease if you loosen the adjustment on spool or does it just stay the same until you loosen it way up. If it lowers as you turn valve out of coupler, I think you are not getting full pull on valve. Those linkages were poor on the 656 and I have repositoned a couple to get more lift on valve. Other wise, you could put in a higher pressure valve. I am not sure if it is a direct exchange of valve like the larger tractors or not. You know, initially a 706 etc was 185 psi and later the larger tractors were increased to 235 psi and I have installed that valve in a lot of older tractors. Requires new valve, nut with seal in it is different and the spacer changes to a thick washer under adjustment nut. I have never seen a pto pump go bad either but if it is bad your low idle pressure would be zilt.

to Pete 23: your diagnosis was correct. We straightened and removed the slack in the linkage, and the pressure guage reads 230 when the lever is in the engaged position. A sincere thank you for taking the time to help. ....Eastern Ontario 656D guy.