Yeah - I put those in as a diagnostic to try to see when the interrupts were happening (and consequently making my missed pulses problem worse...)
Whew! I think I've got it working well enough now so I can move on to the next bit. And I thought the encoder was going to be the easy part...
Thanks everyone for your help and comments!! I was really stuck.
Interrupts are pretty cool! Have never used them before.
--Roy 