maybe this is common knowledge, but brett p from mach3 support just showed me a trick that would have saved me copious amounts of time had I known. when you are single stepping the script, simply hover the cursor over any variable, any line, and it's value will be displayed. I had been adding all these temporary message stmts, running the script, and then browsing thru the history to try and figure out what was going wrong.
hope this helps y'all.