I picked up a “catalogue” return for (read it and weep) £34 (X52 Pro) RRP is about £115. The supplied PS2 cable seems to be a weak link, as others have mentioned it.

When my stick isn’t working, there’s a single green led glowing, but only the throttle works. If you have an old KVM switch lying around, you might have a spare PS2 cable – try that, but pushing the supplied cable in is usually enough for me.