oil leaking Tecumseh engine on Toro mower

2004 Toro Recycler Model 20031 with a Tecumseh LV195EA engine. It's 12 years old and I've only replaced oil, air filters and spark plugs....nothing else. The oil level is at the full mark. It is not over-filled.
 
It's leaking oil and it collects at the front of the mower deck. I've took the engine covers off and cleaned everything up in order to run it and see where it's leaking from. It seems to be leaking only when the engine is running, but it can take a couple minutes before it starts to collect at the front of the deck.

The mower runs great. It starts easily. It doesn't really smoke, though I have seen a couple puffs recently after the oil leaking started. I thought it might be due to oil getting on the muffler, but can't be sure.
 
The oil is not leaking at the dipstick tube seal. There has never been any oil moisture around there. After cleaning the engine, I started it up again and see 2 places of oil leaks. The top breather assembly rubber plug had the lesser leak. The other place that seemed to be a larger leak was at the front/cylinder side of the engine, around where the cylinder fins and crankcase/block meet.
 
I took the breather assembly out and cleaned it. I blew and sucked in the hose that goes to the carb. It made a funny fluttering noise in one direction and seemed to have a more resistance in the other, though I forgot which direction did what.
 
I've read online where crankcase pressure can cause leaks like this. I'm not sure what can cause the pressure. I'm wondering what I need to do to get this leak stopped. If it's bad rings or head gasket, wouldn't it run poorly or smoke?

I recently bought some parts from Jack's to fix the self-propelled function. I need to get this oil leak fixed now.
 
Some pictures - they don't seem to be showing up - sorry.: