I came back to rigid tapping a few weeks ago and had trouble. Find Index (galil FI) quit working reliably, don't know why. I also had troulbe with resetting registers again. Do a search and replace as outlined below. The macro worked with these changes for the last couple weeks.
IF \864=0 THEN COMMAND DP,,,,0:COMMAND GA ,,E :COMMAND GR ,,\860
'if first time through;FindIndex mark,set spindle to slave Z,electronic gear ratio
'NOTE changed to DP,,,,0 on 04 05 09 program bugging on FI
...clipped main program....
COMMAND GR ,,0 'turn off electronic gearing
'MACHHOME3 \868 'current home readout
'MACHZERO ;;\868 'rezero to current home readout
'NOTE: Above 4 lines needed because registers get confused with electronic gearing
READOUT3 \869 'current Z position
'NOTE first four lines above bugging 04 10 09, second trial