dont forget g92 as being a possible cause for error.
Also just to check if the offsets are realy working but for some reason off. I would set up an alternate offset like g55 (make sure its high for crash purposes ) and then make a simple drill program. See where its stops. then add 2" to the g55 "Z" and see if it moves.
If the start doesn't move then its as you think and probably a factory visit problem. If the start point moves then maybe somethin else at work here. I would go into the settings menu on a machine thats working and make sure EVERYTHING is the same as the broken machine.
That being said your probably screwed and will have to badger the factory into coming and fixing.
Michael t.
ps: if you have a new amp you can switch it to another axis and see if the problem floats to another axis (all the amps are the same) if it does get them to warranty the problem amp (make sure you switch it back so they don't give you grief)
thanks
Michael T.
"If you don't stand for something, chances are, you'll fall for anything!"