1999 Lazer Z Burning Oil Until Hot

I have a '99 60" Lazer Z with the 25 hp Kohler Command engine with 730 hrs on the clock. I've changed oil and filters on time, every time and last Spring, it began a nasty habit of smoking profusely while under load, blowing thick blue smoke. I suspect I stuck a ring as a result of sitting through the winter (garaged). I've tried Sea Foam in the fuel and it still burns oil until it gets good and hot, 15-20 minutes after startup.

Any ideas on where to start in terms of a cure?

Sounds like a bad ring. There is no fix other than replacement.

First, before i did a ring job I would pull the fan cowling and see how dirty the engine fins are. If they are caked with dirt and oil, or grass, or even a rats nest, I would suspect a head gasket leaking oil into cylinder. IF you still suspect a stuck ring, then try draining 1 qt of oil and replace with 1qt of transmission fluid. Run engine WOT for 15 min. Do not drive or mow during this time. Drain and replace filter and oil. Mow grass, keeping a eye on exaust. Check again next day, If it isnt any better then new rings are necessary.