i bought my bow from an old man and my screws were still too. i just pulled the allen wrench til it almost broke but the screw loosened up. maybe some penetrating oil? (WD-40) i don't think it'd mess up the limb but i'd cover it up anyhow just to be on the safe side.

the best thing to do would probably be just bring it to a local archery shop.
1. they know what they're doing and have tools for it.
2. if they break ur bow, they'll pay for it