I've been hearing an unnerving creaking when putting force into the pedals for the past 2-3 weeks. I guess that would explain it! Only had solid axles before where a snapped axle failure is rather more obvious and catastrophic, the quick release skewer has put up a good fight...

This example came with a microcassette still in it - handy for testing, and looks like this one has some of the previous owner's programs on it so I'll be interested to see what's on there. Looks like the belts I've stuck in there are about the right size at any rate!