Apologies for reviving this dead thread, but I've finally installed the turn signals (after fixing much more pressing issues), and they keep popping the fuse that I put in! They will usually work for a few button presses, and then pop the fuse. I re-installed the wires into the motogadget switch housing to make sure I hadn't messed anything up in there, and its still popping.
I probably have the power hooked up in a dodgy way, because I noticed that the turn signals work without the bike off, no key in or anything. I connected the power to a post on a circuit breaker that I pulled off of the starter solenoid (wasn't sure which post of the solenoid to use). Should I try a different power source?