One day later and my 300e is back on the road. The air pulley/clutch on the air pump is completely shot so I removed the air pump and installed a shorter serpentine belt for the time being.

The job went flawlessly. I very carefully measured what size belt was needed and bought it at NAPA for $37 (Fastlane sells a much better belt for less but I was desperate). Anyway, the size belt to buy if you are removing the air pump on a M103 is 6PK2365. This number can be used to purchase from NAPA or Fastlane. The belt fit perfectly and car is running quiet. Now I need to see what I can do about fixing the clutch on the air pump.