... If your not sure you're reaching the plug contacts w/ the test leads,
plug the old dryer in
leaving just a smidge of the blades exposed and probe there. Be careful
to not drop lead across and short, etc., etc

Or, pull the rear cover and test at the point where the pigtail is
attached is pretty simple.

Yes, how about just taking the plate off/out of the box and doing the
testing -direct- on the wiring in the wall..
Theres the possibility that one of the screw/terminals is loose or
incorrectly hooked up in there.