Problem with Stihl MS170

[DT_]

Ms170 problem

I recently acquired a used ms170. It came with a 16 inch Oregon bar and chain on it. It fires up and runs fine and the chain moves when there’s no load on it. As soon as I try to cut something the chain stops moving. I replaced the clutch and sprocket and it still does the same thing. I made sure the chain is on the sprocket and didn’t move forward between the washer and the sprocket. Any ideas as to what could be wrong?

 

[Bob Hedgecutter]

Is it a sprocket drive or spur drive? Unusual for a 170 to run a sprocket.
Did you replace the clutch with a Stihl clutch or an aftermarket cheapie?
Is there a needle bearing between crankcase and clutch bell?

My best guess off supplied information is a mismatch of parts and the crank is not driving through the clutch sufficiently to maintain chain revolutions under load.
Photos of the clutch bundle might help.