If the only difference is the torch, chances are that you still have an electronic noise problem. This is hard to understand, because this seemingly electrically harmless change can cause problems. If you have an electrically operated torch control, it may be causing interference with one of the motor drivers, and causing it to generate phantom pulses that move the torch away from the intended path. The proof of phantom pulses is that they will cause the torch X&Y position to not return to your 0,0 reference point when you do a home. I recommend that you make sure that your cables are properly shielded and grounded.