I went to take a quick ride today before the thunderstorms started and I noticed that It was pretty difficult to turn to fuel valve on. When I got home after taking about a 30-40 mile ride I couldn't turn the valve off at all with my hands. I had to use a pair of pliers. Any suggestions of what I can do to fix the problem. It just has occurred in the past week, last weekend I rode it 150 miles and didn't have this problem.