Do you know if the transmission has worked ok after any major work performed on it? Or is this a condition which appeared after someone touched it?
I know someone who
assembled the valve body and, by accident, flipped one of the steel thingies against which the accumulator springs rest the wrong way around.... and this resulted in no fourth gear :-).
This someone had to take the valve body down again to put it together correctly. Thank god for the lift and the drain barrel....
Just what happened to me.... I tried to find a photo, but no luck.
/T