xXBADGERXx

Why dont you just put your hand on the back of the screw that is inside the chainguard and apply some force to it whilst unscrewing , It might wind itself out . I have had this with bolts before where the thread was a bit knackered . Remove the rear wheel and put your hand in and feel to see if the bolt has any thread protruding out , push something against it like a small bit of wood and unscrew the bolt , it might start coming out enough for you to get a set of Mole Grips on the head and wind that bugger out .