Thought I'd post a follow up to this situation. We checked thoroughly and found nothing else unusual. However, the lady recalled having a full bottle of water spill into the back seat.

This combined with my perception of wetness in the padding leads me to believe this was causing the problems. Inspection of the pump shows no evidence of water damage but since this was pure bottled water, I don't expect to see much.

I had removed the back seat to disconnect the battery and left the area open over night and I believe this dried up the water sufficiently to cause the problem to go away.

Thanks again!

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250