Saw Won’t Cut Straight

Rob Stafari said:
Assuming the new bar and chain you put on are a correct match to the saw's setup... that leaves you with bar mount, drive sprocket, bearing, crank, and operator. Take the bar off, give it a healthy compressed air bath. Pull the chain guides, brake covers, clutch drum, and blow everything out. Inspect bearing and land on crank for wear. Grease bearing if good and reassemble. Make sure chain is running even around sprocket and not hitting anything. Even if the cause of the problem isn't there, your saw will thank you. Then make a test cut in clean wood. No dogs, just bar on log, new chain pulling itself through. If the problem wasn't found anywhere else, we are left with the possibility of you applying some sort of twist to bar like the flying squirrel and operator error.
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This is the most helpful feedback, thanks @robstafari. I’ve been running saws for 10 years, I always hand file my chains and dress my own bars. I’ve practically memorized the Oregon bar and chain booklet and refer to it all the time to make sure I’ve got the correct bar/chain combo. I know for a fact that the bar and chain aren’t the culprit because I can take them off and run them on my other saw and it cuts straight as an arrow. I’ll investigate these other issues on the power head and see if I can’t figure out what’s going on.
 
I have so far found this condition in five cases and I am sure there are more - 'still not cutting straight after new chain and bar fitted' :
metal in the stump enough to blunt one side of chain but not two,
Loose dog on one side (or one dog reversed - borrowed saw...dont ask...),
Wrong grip allowing twist,
Worn out vibration mounts allowing powerhead to twist relative to bar,
Cutting too low on stump where highly dense and twisted grain pushes the chain towards less dense and less twisted wood usually on the stump taper,
 
Sounds dull, but have you checked to see if the chain tensioner is engaging properly with the bar? and that the side cover is fitting flush.
 
HigherGroundArborist said:
The culprit!! My clutch drum assembly was damaged somehow and that is what was causing my saw to pull to the left every time. I’ve never seen or heard of anything like this happening. Now I know!
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I'm not familiar enough with the part to recognize the specific damage in the photos. Are you saying that having replaced just this part the saw now cuts straight (with the old bar, the old chain, etc?).
 
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