When I had my rear passenger tire off yesterday I noticed one of the two rotor bolts was missing. I was reading Goatman's wheel bearing removal / replacement article for a 200 series car recently and remembered his instructing to remove these during the process so I went to his article. His bolt, it appears from the photographs, is a hex head bolt instead of a phillips head bolt like mine.

Questions:

1) Did older models use phillips headed bolts or did Goatman change his or did someone change mine at some point? I would like to replace mine with hex. Either way what is the head size, length and thread pitch, etc. for this?

2) When on a lift, the brakes don't work on that wheel and there is fluid on the tire and seen on the rotor also. Are the pistons stuck out because of the missing bolt? I plan to investigate further tomorrow but wondered if anyone has ideas or experience about this.

Thanks