My 1977 5269G needs help. It's pretty much worn out and in need of a rebuild, but I am trying to keep it going for now. There's a brass plug in the crankcase (about 3/16" in diameter)...toward the backside of the mower right by the cylinder head bolts. It looks like it's leaking oil around it. I know for sure that my D-481 did not have this, and I don't remember seeing this on any of my other D-series. What is/was it for and can it be sealed up without screwing up the crankcase? I think this is why the mower is so hard to start and runs like crap until it warms up. Crank seals look ok and everything in the carb is new.