OK. I figured out what I bungled. The problem was the G04 (Dwell) command. According the G-code book I was reading (Peter Smid, 2nd ed.) the P parameter is in milliseconds. When I closely read the Mach 3 G-code documentation, it said P could be measured in either seconds or milliseconds depending upon a configuration option. I wanted to wait 2 seconds for the flood pump to come on,
so I did "G04 P2000" to wait 2 seconds (2000 mSec). Instead, the Tormach interpreted "P2000" as 2000 seconds (~33 minutes.) The "Nothing to Feedhold" message occured as a result of me hitting the [Space] bar while it was patiently waiting for a 1/2 hour pause to expire. Of course, the solution to the problem was to switch over to "G04 P2.0" and everything worked fine.
Thank you for explaining what "Nothing to Feedhold" really meant. That provided the useful insight that it was my dwell command that was the problem.
Thanks,
-Wayne