Does anyone use this stand or one of the other similar models?

I bought mine from craigslist only to find that I cannot lock the arm into place, so I cannot rotate the bike and keep it in that position. It has a handle at the back of the arm that I believe you should be able to flip to lock the arm in place but mine flips freely back and forth but does not lock into place.

Anyone had any experience with this problem?

Thanks.