Lagun 310 Z-Axis Over-run

[eross]

I have an old Lagun 310 that is consistently overrunning the Z home position on M30. This results in a higher than zero when the tool comes down into the next part. It will do this until the Z hits the limit switch, at which time I have to power down, manually lower the Z off the limiter, and retouch my parts. I've looked everywhere to find a solution and so far nothing is working. I've checked axis lag, Acc/Dec in parameters, backlash, everything. If I fed back to home, no problems. Rapid always overshoots by .005-.007. Any ideas how to fix this or at least patch it?

[eross]

To add to the above, I've replaced the keys in both pulleys for the z-axis travel. There was significant play that was resolved. However, overrun condition still exists. Any ideas?