Hello Blacktrain11,
I speculate a sticky valve & valve guide, but a loose valve seat is a familiar problem on those engines if they have been overheated multiple times in the past.
It is good verify your compression test gauge is not acting up. Is the Schrader valve in the end of the hose snug?
If you are using and old push and hold style compression tester, they are not very reliable especially with age and wear'
It would not hurt to add a couple of tablespoons full of Marvel Mystery oil to the engine oil and see if things improve. That stuff does wonders, but don't overuse it. MM oil is a great product for diluting sticky carbon and freeing up sticky piston rings and valves.
If you try that, run it like normal for a couple of hours, then change the oil and filter.
At the end of the cutting season do the same process again.
