It's a Poulan Pro P1500 trimmer.
Carburettor was changed recently and has been cleaned.
Fuel can be seen on the spark plug once it is removed.
Inline spark plug tester shows that ignition coil is fine.
Brand new spark plug.
Muffler and air filter were cleaned (even with air filter removed the engine won't start).
The piston ring is not sticking.
I've changed the gas. With both gas samples, two-stroke oil was mixed properly.
This trimmer was running fine just a few days ago, what could have changed?