I have an older echo 360t with a 12" bar and full comp chain. (ATV 'trail-saw') I keep it sharp and it runs well but I can stall the chain (not the engine) if I lean on it too hard. Is this normal? I admit I'm cutting wet, dirty trees--downed across a trail--and I'm also a novice. If I let off and take my time it WILL cut...am I just being impatient or is there room for improvement / worn-out parts? Is there a clutch shoe 'spec'? or minimum thickness of the shoes?