Just when I thought I had seen everything, this is a new one for me. A friend who knows nothing about chainsaws and should not be using one, showed up with a nice Homelite 47 (that's a Canadian model of the 290/340) that he had acquired and was using at his cottage. He was concerned about the chain getting loose and took it over to his neighbor to get advice on how to fix it. The neighbor, who was a mechanic but also knew nothing about chainsaws, assessed the problem and decided that the bar must be slipping if the chain was getting loose. His fix was to bond the outer guide plate to the base of the bar by spreading rubber cement between the two, then pulling the bar out by hand until the chain was tight (didn't know there was a screw for the purpose), then tightening the bar nuts until they were about to strip. He finished off by putting a dab of yellow paint on the bar nuts/studs so he could tell if the nuts were getting loose again. It gets worse. He used so much cement that it got squished into the oil holes on the bar and completely blocked oil from getting to the chain. The "fix" made it impossible to adjust the chain again and prevented the chain form getting any lube. I may post another thread about why the saw wouldn't run and what else had been screwed up.