You probably already have this, but if you don't'
I'm not familier with Weathermatic, but if the plastic gears get stripoped or even lose a couple of teeth, you'll have problems. For the cost of a new head, (on-line it's $10-$12 - Store front suppliers will be a couple of dollars more) replace it. If you replace it with the same make and model, you should be able to unscrew the top of the new one, pull the guts out, and do the same with the old one - without haveing to dig up anything. You might have to clear a little of the turf and soil from around the old head to get a grip on the cover.
Slip the new guts into the old housing, close it up and adjust it. If it's that close to the house, prepare to get wet.