A few days ago, after removing the zorst can, I fettled the rear caliper on my mk1, cleaned the pistons and caliper, re-greased and bled through some fresh fluid. Noticed at the time that one of the bleed nipples was a bit wobbly so ordered some new nipples.
Anyhoos, decided to fit the new nipples today, first one went in, a bit fiddly with the zorst in place but managed with a socket and rachet, second one went in, started tightening it up with the socket and after a few turns it went pretty stiff to turn. Took the socket off and noticed the nipple had gone in at a wonky angle.
Soooo, removed the caliper and got it on the kitchen table workbench and clamped it up ready to tap the hole. Tried tapping it but it just wouldn't straighten up. Ended up chewing up the thread.
I've just ordered an 8mm helicoil type kit.
If it aint broke, but a lil bit wobbly, don't fix it !
On the plus side, yamaha nipples are £10 each, I found and got 4 alternatives delivered for £4.