Having a problem with the cassette tape deck in our 1992 300SE. The stereo (radio) sounds fine and the cassette tape deck when on side 1 sounds fine. The problem is only with side 2 of any cassette. The sound is muffled and with lower volume. I purchased a tape cleaning cassette but the Mercedes tape deck rejects it and will not allow it to be inserted. The tape cleaning cassette does go fine into other tape decks we own. The other tape decks don't "pull" the cassette in. Any suggestions?