Did a search but didn't find anything about my problem. I have a Troy-Bilt TB525CS trimmer/tiller/pole saw. It ran fine a few months ago. Now when I pull to start it, it feels locked up. l removed the plug and it pulls smoothly. The more I screw the plug back in, the harder it is to pull, until it finally won't move. I'm wondering if a valve is stuck shut. Appreciate any comments or suggestions, thanks!