Well, after buggering up the attempted resoldering of the U2 chip (my Lidl soldering iron died & my spare is crap) I decided to make my own. I probably should have done this in the first place rather than buying replacements.
I took some spare LEDs that I'd used to make my DRLs (I think they cost £4 for 10), drilled a hole in the internal case, reassembled, soldered & job's a good 'one.
Only thing is the light is yellowish rather than blue... must try to get some better LEDs at some point...