Well, if you look in the thread I just made, the last two pics show the RSMs. Overtime, they deteriorate inside. You can either replace them yourself, which isn't fun but can be done, pay someone to do it, or live with the bump.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>