Truth be told, I think the repair depends on the owner and the car. With an E500, I would not attempt an unkown repair. If it was a 1986 300E with a bajillion miles, I'd be tempted to try the sealant and just hope for the best. Knowing me and my finickity nature with cars, I'd replace the unit, but I would understand someone with a car worth $3500 to try an economical repair...
1998 C230 "Black Betty"