Hope your batting average is better in softball... Sorry, that was too good to pass up.

Anyway, if I remember right, the bolts have round heads which make it difficult to grip it with a pair of vise grip. If the hole is not too rounded, see if you can insert the next size wrench in there. Also, maybe try to wedge a flat head screwdriver into the hole. Just remember to protect that frame.

edit: HomeDepot and Sears have screw extractor if it comes to that.