I bought a used Stihl ms260 and have cleaned it up with hopes of having a good saw for cutting firewood for personal use. I thought it was ready for action when I found that the chain either gets real loose quickly or tightens up to the point of stopping the chain. I took the bar off and inspected the tensioner. It appears to have some sort of problem. I can wiggle the pin that goes through the bar and it moves 1/8"-1/4". I am no expert but I think it should remain rock solid until the screw is adjusted?? Does this sound like a simple fix? What are the potential problems? Thanks