Thanks, but I'm not sure that's it. I've opened it up and the sequencer enable switch looks fine, can't see any obvious corrosion or other visible problems on the circuit board.
Although you're probably right in that it has something to do with the sequencer - I just noticed that that hitting the "step" button does cycle the value number up. Also, hitting "cancel" changes the program no. display from 1.7 to 1.8 for some reason, but nothing else is responsive.
Zack