clutch?

I once had a small piece of wood get wedged inside the nose sprocket and locked the sprocket up. Can you pull the chain through by hand with the engine shut down?

Thanks, it wasn't a piece of wood ... but something had caused the chain to seize on the bar to the point that it could not forced to move. A few clicks to loosen it, and it works fine again.

is your oiler working?

Sounds like either the chain was too tight within adjustment and or not suffient oil getting to the bar . The bar having more mass heats up and expands more than the chain which causes it to bind .

Actually, as it turns out, the blade became tightened to the point it was bound to the arm --- just loosened it and it worked fine. Don't ask me how the blade tightened rather than loosened.

Yes that is what I advised . Proper terminology is chain not blade and bar not Arm lol . Cause is as previously advised and your welcome.

Ssewalk1 ... yes, thanks!!!

A quick rule of thumb , solid bar chain adjustment at mid bar is 1\4" chain deflection . Roller tip bar 3\16 " chain deflection . This will ensure chain will not bind , when bar expands. The tip of the chain tooth should not be exposed when pulling on chain to test the proper tension.

Thanks