Hi, I've had a similar issue and it looks like it's bar wear. I measured the circumference of a new bar against my old bar and it was significantly less, however, new bars are difficult to order from Ryobi. I have 2 Stihl chainsaws that have the original bars and have been heavily used for over 10 years, the Ryobi bar is only 18 months old. The problem may be that the Ryobi bar is comparatively very thin so the tip-curve is very tight and prone to premature wear. The Ryobi tightening mechanism also has very limited travel, so once the chain is slack, then a new bar is needed, even after removing a link as a stop-gap measure.
