A seized motor IMO is always worth looking at.
Had a bad storm one late summer evening at my home, that knocked some large tree limbs down in my driveway. Got in a hurry (mistake), grabbed the chainsaw and my two cycle gas can. I always run my chainsaw dry at the end of wood cutting season in late February.
Filled the tank and started cutting. After cutting for about 20-30 minutes, the saw bogged down and cut off. Started it up and continued cutting. Saw bogged down and cut off again. Wondered what is going on? Is there a hole in the fuel line?
I was getting pretty ticked off at it.
The fourth time it cut off, I grabbed the rope to start it up again, and liked to have pulled my arm out of it's socket.
Then I knew what was wrong, but it was too late. It was locked up tight as a tick. Yes, I put straight gas in it, because I thought the oil was already in the gas.
Went in the house to calm down.
Came back later, took the plug out, and sprayed some PB in the hole. Let it sit for about 30 minutes and took some pliers and tried to turn the crankshaft. After carefully applying some pressure, working the crank back and forth, the piston finally broke free.
Mixed up some gas kinda heavy on the oil, and put it in the saw. It ran ok. I finished cutting up the limbs so I could get out to go to work in the morning.
That was two years ago, and a lot of trees cut since then! It's still cutting fine.