You should probably post your question over at the Acorn help forum over at Centroid. They have knowledgeable people there ready to help. You will likely get an answer fast there. Make sure you read the post on how to ask for help. They will want some specific information in your first post.

My guess is the Z motor is overloaded.

https://centroidcncforum.com/viewfor...9fe6e4e1248a17