Hi guys and gals, this is my first post on the forum and a mishap during the first real work that I have attempted to do on the engine.

I have just replaced the valve stem oil seals in my 1985 300 W123TD-T after reading many how-to's and watching video's online. I remembered to block off the timing chain orifice with a rag but I didn't realize that the camshaft pedestal at the other end had an orifice beneath it. Incredibly, in the last minutes of the job my oily fingers dropped the lock-nut which found it's way into that orifice. Could the nut be stuck somewhere or, hopefully, would it have dropped thru to the upper oil pan where I might be able to reach it after removing the lower oil pan?
As an aside, I have read that the crank should always be turned clockwise but I have never been told why. Is it ok or not to turn it back a couple of degrees if one overshoots the timing mark slightly for instance?