Turn the chain brake off, then remove the side cover (back off the adjustment screw several turns first). Clean the oil ports in the rear of the bar and the area around the oil outlet port. Fit the chain to the sprocket, then work the bar into the chain and pull the bar outward to tighten the chain. Fit the cover back making sure the adjustment tang drops into the large hole in the bar. Run the mounting nuts up finger tight, adjust the chain so that it doesn't droop from the bar, but allows the chain to be turned by hand, then tighten the nuts and recheck chain tension. Hope this helps!