Well, the gasket arrived today and I reassembled the engine. After cleaning both the block and the oil pan, I greased the surfaces and pressed the gasket into position on the block. I carefully lowered the oil pan down and torqued the bolts in a criss-cross pattern. After getting the motor back on the cassis and putting all the other bits back in place I started it up. It was difficult to start and I think there is an ignition problem that I'm going to start a new post about. I ran the mower long enough to get it up to full temperature AND THE DARN THING IS STILL LEAKING! The oil leak does not seem as bad as before, but it is right in the same area with the same symptoms of oil seeping down onto the mower chassis just below the piston cylinder and somewhat to the muffler side.
There aren't any other sources for this oil that I haven't checked and put new gaskets on. I looked at the block and oil pan and there were no obvious cracks or other defects that could leak. The gasket surfaces of both parts were not severely gouged or otherwise damaged. I'm at a loss as to where the oil is coming from. I guess I'm going to have to learn to live with it and be sure to top the oil up from time to time.
There aren't any other sources for this oil that I haven't checked and put new gaskets on. I looked at the block and oil pan and there were no obvious cracks or other defects that could leak. The gasket surfaces of both parts were not severely gouged or otherwise damaged. I'm at a loss as to where the oil is coming from. I guess I'm going to have to learn to live with it and be sure to top the oil up from time to time.