EMC2 Screw Cutting Problem

Hello group, this is my first post.
I would like to use my lathe with EMC2. I have set it up successfully
in the past with both Mach 3 and TurboCNC. The problem I have is with
screw cutting not functioning. Both axes move very smoothly and the
spindle index signals (1 ppr and 48 slots) show up with good clean
pulses in Halscope, so I know communication is ok. When I run one of
the sample threading files all goes well up to the point where screw
cutting starts - then the lathe stops and EMC2 waits at the G33 or G76
line like it's waiting for spindle pulses. Does something else need to
be setup in the Hal or Ini files? I might add that my programming
skills are about zero so any answers must be in plain english please.
One other thing - would it be hard to get spindle speed on screen? Many
Thanks, Martin.