If you are not fouling plugs, carboning up the exhaust or generating lots of smoke I wouldn't worry. 2 strokes are not known for their efficiency.

Two stroke engines by their design comsume a lot of fuel/oil mixture and as noted are not very efficient. A fair amount of mixture is actually converted to mechanical energy to run the mower. Unfortunately the design partially combusts quite a bit of fuel. You see the residue as as smoke and sludgy carbon build-up.

It was a useful design when we needed a cheap to build engine and were not worried about the about cost of fuel and pollution. Times have fortunately changed.

You don't have to convince me. Regardless of how Lawnboy afficianados feel about these mowers the only reason I keep one is as a curiosity. I'd never buy another 2-stroke mower even if they were still available.

Might have a loose jet or a sinking float, but you should see a lot of oil smoke assuming you're using a traditional mix. The only way you can be running over-rich and not see oil smoke is by using a 'leaner' oil mix, like Opti-2 or similar.