Have two trucks (same ones as previous) that are having odd problems. The sideshift, with a load, will shift one direction fine; start back the other way, it works ok untill the operator stops. It then stalls there. It has to be shifted in the opposite direction slightly to continue. Carriage bearings and slides are ok, pumps have been replaced in an attempt to correct the problem, fluid and filters have been recently changed, and the carriage is shimmed ok. We're scratching our heads.