Oreo,

Since you have done a ton of work to get as far into your Benz's innards, I second BusyBenz' idea of lubing wiper's internal mechanism. It is a bit more effort (do a search - there are some great posts w/pix that show how it is done). If you do not do this now while you are right there, you will really hate having to do this again later if the dried up lubricant inside the wiper gives up the ghost. Re-lubing made a nice improvement in wiper's operating smoothness when I did this.