Thanks, DT, for the suggestions.

Update: I re-spun the code entirely. Got rid of the interrupts altogether and set up everything to poll the needed register flags.

UART2 works perfectly to capture the MIDI data - all of it - and the numbers generated by Mister-E's baud rate calculator are spot-on.

My main loop is massaging UART2's data and re-transmitting at a different baud rate through EAURT1.

Thanks to all for the input. At some point I may re-visit this program and try using interrupts...