This machine has a "Cam" type ATC system. Now and again the ATC fails to complete and has to be recovered manually by winding the ATC motor to get the arm back to home position. Doesn't always fail in the same part of the tool change either.
Have checked inputs from tool pot sensors,spindle, tool change position. Have checked that the ATC motor brake is releasing. Have changed relays and contactors for the ATC motor run. The thought now is to perhaps swop with another machine the ATC motor, but thought I'd present this post incase someone recognises this problem or can offer some suggestion?