Graham,
Now I am really confused - for the past two years I have been drilling holes with Mach using helical arcs, produced with EdgeCam. I tried turning helical arcs off in EdgeCam and I still get the same error reported but on a different line. The code below is a drilling cycle using what I thought were helical arcs. If they aren't, please tell me what they are and I can re-set my brain

Thanks,
Mike
%(TAILPLANE HOLD DOWN)
G90 G40 G49 G64
(DEFINE OPERATION : PROFILING OPERATION)
T01 M06(5mm End Mill)
G1X65.0 Y10.75
Z0.0 F100.0
G17G3X65.0 Z-1.0 Y10.75 I0.0 J-3.25 F500.0
X65.0 Z-2.0 Y10.75 I0.0 J-3.25
X65.0 Z-3.0 Y10.75 I0.0 J-3.25
X65.0 Z-4.0 Y10.75 I0.0 J-3.25
X65.0 Z-5.0 Y10.75 I0.0 J-3.25
X65.0 Z-6.0 Y10.75 I0.0 J-3.25
X65.0 Z-7.0 Y10.75 I0.0 J-3.25
X65.0 Z-8.0 Y10.75 I0.0 J-3.25
X65.0 Z-9.0 Y10.75 I0.0 J-3.25
X65.0 Z-10.0 Y10.75 I0.0 J-3.25
X65.0 Z-11.0 Y10.75 I0.0 J-3.25
X65.0 Z-12.0 Y10.75 I0.0 J-3.25
X65.0 Z-12.0 Y10.75 I0.0 J-3.25
G1Z5.0