First of all the bushing is a seperate piece that presses into the rear carrier and can be serviced seperately. Check it carefully. It is a strange bushing. I don't think it has any rubber in it. Rather it is steel sealed grease unit like a lower ball joint that allows a wobble type movement. It is like no other bushing on the car or most cars. If you don't know how to examine, have someone who knows examine it. But then again you may have found the problem.

__________________
1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T