Got the bike out of the garage on Monday morning and noticed the rear wheel rubbing. Most odd. Then I spotted the reason - a spoke breakage, snapped at the end of the threaded section, just inside the nipple. Probably happened on the short section of bumpy trail I went down at the very end of my ride on Sunday because it had been fine for the rest of the ride.
It's a cheap off-the-peg wheel and I've been suspicious of its build quality before, so rather than just stick a replacement spoke in (it came with three spares), I went round the whole wheel and loosened off all the spokes so I can do the job properly. Some of them seemed to be very 'wound up'.
I note that some kind of threadlock seems to have been used in the original assembly. Is it worth completely disassembling the wheel, cleaning the spoke threads and rebuilding with fresh oil?
I believe the current spokes are Sapim D-Light, so should be decent enough quality.