Servo shaking problem.

Ok, now onto the next step in recommissioning the winder. This winder has three servos that are supposed to spin slowly to a certain point when you hit "origin return" (essentially a home from what little docs there are on this machine.)

Instead of doing this they oscillate back and forth without ever making a full revolution. Eventually Error 414 is displayed on the handheld.

Can somebody point me in the right direction regarding the relevant parameters I need to be studying?

These are "red cap" servos BTW, the controller is a PowerMate H

Thanks in Advance