I made the mistake of attempting to rebuild my 1990 760 turbo AW71 transmission. I purchased the Volvo factory manuals, and followed the specs to the letter. I corrected the problem that I started with (no shift up into fourth),but now the car won't go into reverse after it's warmed up. When cold, the car drives and shifts normally, but after about ten minutes of driving the transmission starts to whine or "sing" ( sounds hydraulic-doesn't change pitch with RPM, but does change pitch when I pull on the kick-down cable with the tranny in PARK). I pulled the valve body off and dismantled, cleaned and reassembled it. No help. Checked the accumulator pistons, and they seem normal. Springs are in the correct locations, I think. The kick down cable moves freely. What an adventure. I'm ready to spring for a rebuilt unit from the dealer ($2000), but I really hate to admit defeat. Anyone have experience overhauling these units?