Hi Tweakie and Dave,
Thanks for helping and the effort you put in the problem.
I now installed the newer version R3.043.066, and that version runs the partprogram OK.
But I now see other strange things. While running the part program and observing the Mach3 toolpath screen, it stroked me that while the active point was drawing instance 2 of an instrument hole, Mach 3 was highlighting the first instance of that hole. See the attachment.
This means that Mach3 does not completely release subroutines and their waste data after they have been used. I encountered similar things some time ago when I was trying to use tool compensation within subs. That clearly did not work and as far as I know, has not been solved yet. That was the reason I hesitated to buy and still work with the demo version. I think there still is a major issue within Mach3 with subroutines.
Wilfried.