The wife has a 2014 s80 with electronic parking brake. I recently did the back brakes and followed the manual instructions got everything back together and there is a clicking sound coming from them. Tore back apart checked everything and still it's there. Sounds like when as a kid you put something in your bike spokes. Had a mechanic buddy look it over and he said everything was right. Anybody have any thoughts on what it could be? All help is appreciated as it's driving me nuts.