140 series windshield wipers
 

I have a 1995 S-350 (140 series) with windshield wiper problems. About 6 months ago the wipers started working slower and slower until they finally stopped. Some of the interior dash guages and such were operating strangely also. The dealer replaced the ignition switch and solved the problem. Now today all of a sudden the wipers started operating slowly again but all interior guages and dash lights are working properly. I was told by a mechanic to try and lubricate the linkage and will do that tomorrow. Is there any way to load test the wiper motor and how many amps should it draw? Could the ignition switch be bad already and why does this impact the windshield wipers? Is this a common problem on Mercedes? I have owned many vehicles and have never had a wiper problem before this. Oh for a service manual on the 140's!!! Any one have a dealer service cd that you could burn me a copy$$$$ Help!