I have an 1811 too and the starter began to spin but not crank the engine over.
I just removed the left side sheet metal from the engine and with a long thin screw driver was able to pull the Bendix gear back towards the rear and pressure wash it off after a turn or two of the starter. I then sprayed it with WD 40 and that was a year ago with no further trouble. I really don't know what there is to clean other than the gear. It is a sealed motor with pre-lubed bearings with no oil holes.
