you would have to increment all your Z's to move down the same amount, correct?
#103=0 (make sure this is done too in the main)
#103=[#103-#100] (add a step down just for the arcs)
example Z[1.545902+#103]
thou I have to admit I don't remember creating 3d arcs like your trying
but if it runs your one loop fine now, then I see no reason that adding the step down should not work.
your original code;
G91 Z-0.001 (step down 0.001 per pass)
G00 X0.250409 Z1.500977 "This is an incremental move too, but to where
?? from where
??"
G90 "set it back to absolute moves"
I thought your original start depth was Z1.500977 now its 0
but admit I did not look close and notice that was an incremental position from who knows where, as there was no reference position move before it.
So not sure wtf your up too really or where your starting at.
Scary code, as your original code started, going vertical then step back down.
Re-think your approach
always look one line at a time and say to yourself "from where I'm at, what setting & position do I need to get me to the place I want to be next"