I had a similar problem with the Zaxis creeping during program run. It turned out to be noise on the z encoder for the servo. I had used the supplied encoder with the motor which was a six wire encoder (renco) instead of a four. It had an a and b channel but also had a not a and not b channel. I just hacked them off and used four channels. Apparently, this makes the encoder very sensitive to noise. Long story short, us digital sold me a replacement correct encoder and I rerouted my shielded cable and the problem was resolved. Just something to think about.
Good Luck
Billyjack
:cheers:
billyjack
Helicopter def. = Bunch of spare parts flying in close formation! USAF 1974 ;>)