recently the brake pads on my 1989 300 E were replaced by a talented friend who has a number of older (than mine) mb's that he keeps in top shape. now sometimes the brakes make a grinding sound at the very end of braking to a stop and fell like they are letting go. also the braking sometimes has a pumping feeling and the abs light will come on for no apparent reason.

any suggestions for repairs would be greatly appreciated. thank you.