I have a pair of these. Out of curiosity I adjusted one side to it's highest tension to see how difficult it is to unclip. When I tried to adjust it back, the bolt got jammed. I have since rounded off one hex key as well as the bolt itself trying to get it back. I've tried locking pliers on the outside of the bolt with no success.
The threads on the bolt seems to be fine. It will turn right (tighten) but not left. The little plate it's going through to put tension on the spring turns slightly when I try to loosen it. This makes me think that when I do try to losen it, that plate tries to twist out of alignment w/ the bolt, making it impossible to turn.
I've tried lubricating the threads w/ Boeshield and haven't had any luck. Has anyone else here had a similar problem? Is there anything I can try? This'll learn me not to skimp on pedals (there were other problems with this things).