Look through the exhaust port, and check the piston and cylinder for scores, or scratches, running vertical or up and down.

If it's a "Ringed Engine", use the end of a wooden popsicle stick cut square ( Never use a metal object! ) and press on the piston ring. If the ring is NOT broken, you will feel the "spring" in it. A piston ring's "spring" feeling is very slight, but it will be there.

Inspect the glo plug threads in the cylinder head.

So... Bring the tools needed for muffler removal, popsicle stick, glo plug wrench, and if you eyesight is like mine (which I hope it isn't )...a flashlight and magnifier!

Keep in mind that an engine is the "Heart" of any machine!