2006 Bonneville RR disk brake problem
 

Hi, I,m new to this forum. I have a 2002 Bonneville, my problem is with the right rear disk brake. about three months ago it started making a grinding noise, I removed the wheel and found the guide pin on the pad had worked out of the notch on the wheel cylinder/piston. The piston had turned.
I put it back in the notch and it was ok for two weeks then samething happened. I replaced the pads with new ones and about three weeks later it did the same thing.
Question, do I need to replace the wheel cylinder? Is their an adjustment I can/need to make to correct this issue? I have always worked on my cars but this one has me stumped.
Thanks,
Bob