So I've inherited a 1973 Bobcat model 610 and I have zero experience working on them. When I first got the machine it wouldn't move and was shooting oil out of the drive sheave. I put a seal kit in drve sheave and it no longer leaks and operates well. When I open the side case covers all four clutches were wiped out. I replaced all four and It now runs and steers fine. I have a hydraulic problem however, with the bucket tilt. Initially the bucket wood curl upwards but fall back down without constant pressure on the pedal. I opted for the easiest fix and repacked both tilt cylinders with new O-rings and seals...no change. I now suspect the problem might be with the cylinder tilt control valve. Can anybody tell me if I'm on the right track with this? Can it be serviced while it's in the machine or must it be removed? I've read here in the forum that they are a bear to get out of the machine. Any help would be greatly appreciated.