Hi, i have a problem with my bike involving the chain adjuster bolt. When i went to loosen the bolt that sits against the swingarm to adjust the chain tension, i can't get it loose now because it has lost its thread and my screwdriver wont grip to it. And without that bolt loose I cant move the other bolt to move the rear wheel back. So can anyone tell me how I can remove the bolt now to fit a replacement bolt so I can adjust my chain again? Thanks.