Hi, I am currently working on a 1992 Okuma Howa act4 lathe fanuc 15tf. I have this problem where the machine zero ref. point seems to wander +-5mm between power offs. This happens for both x and z axis. Machine decelerates and finds the zero point every time without error, its just in a different place than before. I checked the zero proximity switches and cleaned them, but no luck. It has incremental encoders, so it shouldn`t have any axis batteries right? ( well I couldn`t find any). It has no problem with accuracy, so I think the encoders are fine. Maybe the zero return prox. switches are just getting old and need to be replaced? Maybe this is caused by some software offset or parameter? I really don’t know what should I try next. Machine is usable as it is, but its PIA to offset both axis before every use.