I changed the rear brake pads yesterday. I was fussing around with a screwdriver trying to figure out if there's a way to adjust the parking brake through the little hole and I pushed the rubber cap from the maintenance hole in the hub by mistake. Of course i tried to remove the disc but it's pretty much impossible to remove the 2 screws that hold the disc in place (8 yr old, never opened). Do you guys think it's safe to drive it like this? Should i buy a new cap and put it in place and leave the old on in?
And how can you adjust the parking brake cause mine is pretty much useless right now.

 

Get an impact screw driver to remove the useless screws, or drill them out. Then remove the rotor and get that out. The inside hub is a drum style parking brake. That rubber screw you popped in is the hole to adjust the parking brake. Its like a spur located towards the bottom of the drum. You will see it when the rotor is off. That or you can try to adjust it at the pedal