I assume 1st reverse and 2nd, 3rd, 4th forward work ok? If so, then I believe you have a linkage problem or possibly the lever or detent in control valve are broken. The forward/reverse valve shifts when you shift from neutral -to- forward or neutral -to- reverse. Remove the side covers from the shift console and watch the linkage while you make those shifts. If it looks like the linkage is moving the same distance for forward and reverse, then you need to look under the cab to see that linkage. Have someone else make the neutral to forward or reverse shift while you watch linkage move. If linkage is moving equal distance in both directions and you don't see anything bent, then the problem is likely inside the shift valve.
Hi, thanks for that information so far,
We actually checked the linkage so that should be ok.. After this we drained the oil and took the valve body off from the bottom of the housing, all the springs and o-rings in there were looking good to me so far. We also did the same with all other plugs that we could getting on from there.. But now I belive there is also some valves in the front cover that should be checked too.. We are going to split the tractor now unless somebody has any other idea a guy can do before this happens?
I wouldn't recommend splitting until further checks are made. Have you checked pressures? There are test ports on the bottom of the transmission for checking forward, reverse, 1st, 2nd, 3rd, and 4th clutches. I would also check lube pressure in each gear position. If you see a drop in lube pressure for any gear/s, that is an indicator of a pressure leak in that element. If you find a leak, then yse you need to split to repair. You didn't confirm if I am understanding which gears are working, but from what I understand, it sounds like a linkage or valve problem. No need to split for those repairs.