Play in wheel

[Niall]

Hmm are you sure that'll fix it? Unless that was lodged between the hub and the wheel I don't see it being able to cause that big a problem, plenty of people actually don't have that screw in at all to hold the discs in place.

Also removing the calliper is a socket wrench job (17mm IIRC) rather than an allen key

19mm

Pretty much what scott said. I dont run any retaining screws as they are just a pain in the arse when it comes to removing the discs. Unless that head was jammed somewhere, keep looking!