How to open up windscreen wiper gearbox?

[stiffy]

I have C180 with single wiper. The extender mechanism goes out of sync because the gear inside the gearbox is slipping on the shaft connecting it to the cam arm under the top cover. It's ~ £400 for a new gearbox so if I can get into it I might be able to fix it. It's a closed unit but I figure if a human closed it a human can open it. HOW?? Anyone got any thoughts? I'm a pretty competant and equipped engineer. There's a hole in the top case and one in the linkage that can be aligned to give access to it but there's only a small head in the hole that doesn't look like it unscrews. Also the screw head in the centre of the cam arm is cross head but too shallow to be an ordinary screw. If no one's got an answer I'll get in there with a hammer, see how it works and post how it comes apart. Stiffy. :x

 

[grasmere]

Have a look at the previous post (link below) on sticky single wiper.

http://forums.mercedesclub.org.uk/viewtopic.php?t=5132&sid=a593bd119b08fe7af5c766464b10300d

There is comment on the various types of single wiper that may answer your query

Good luck

Ian