Originally Posted by
Homebrew01
If the bolt's stripped, it's easy to see. Inside the spinle is harder to see, but threading in a good bolt, you can feel if the threads are ok.
Is this a square taper crankset ?
Yes, I’m fairly certain the retaining bolt became loose and stripped out under pressure. Perhaps it was removed for lubing and wasn’t properly torqued when reinstalled. Yes, I believe it’s a square taper but it’s at the LBS right now.