The "flexing" is an interesting theory, I'll look into that at work today. The bracket that all accessories mount to is very heavy duty, I'd guess 3/4" aluminum plate, as you mention the crank pully on the other hand looks kind of light duty, I'll definatly check into that today. If it comes to it, can you get me in contact with the machinest you are useing? Also you may want to look into a stronger belt as I did (see below).

At this time the client does no want to spend the time and money to convert to a "toothed" belt. And wants to try again with the ribbed belt.

The belts used thus far are a standard ribbed belt manufactured by Gates. I contacted Gates and they can supply a "Race" belt, they also sell the same belt in HD, that should help. I am now trying to source idler pulleys with shoulders on them hopefully preventing "walk off". Do you know of a source for something like this?

Thanks for the reply!
Mark