I had this happen on my old 87 300E about 8 years ago or so, and it just happened on my parents 91 300E last week. On my car it was the blower motor, not sure what it is on my parents car yet. You can buy the motor without the cages (quite a bit less for the motor only), but I remember having a difficult time transferring the cages to the new motor and getting it to fit properly under the bracket. I think it was because the stock motor was the original MB part and I bought an OEM motor instead.