Major Oil Leak

It is from my Honda. My Honda HR214 mower! I have it close to 30 years and it has been running like new until this morning; never smoke or gave me any trouble. It develops a major oil leak. I can see oil pooling on the mower deck. What is wrong with it? The piston rings? Head gasket? or ... ? Is it worth DIY, take it the shop or just time to get a new one? This one of the old one with the nice aluminum deck which no longer available! A new one the cheapest I see is $400 plus tax! :-(

Overfilled with oil? Drain plug Leaking?

V-Tech kicked in and knocked the rod out?