Long story, but the end cap in my Dura Ace 7800 cranks was rather stuck, it was greased when it went in but that was several years and about 15000 miles ago, so I wasn't too surprised when it wouldn't budge.
Eventually got it out by putting tool in the vice and turning the frame, unsurprisingly it left a significant amount of thread in the axle, boo hiss.
It's an alu end cap, and the axle's steel, so I'm sure it'll clean up alright, but has anyone had to chase one of these with a tap before? Looks like an M20, not sure of the pitch though, thinking 1mm. Don't much fancy new cranks, and not being open at the other end like an MTB one I can't preload it any other way.

