I decided to change the oil in my little mans 50 and everything went fine I broke the oil plug bolt loose with a 17mm socket and took it out with my fingers let the oil drain out leaned it over and all that. After the oil had drained I tried to replace the plug bolt and it will screw in about half way then it fells like it bottoms out. I have search the forums over and can't find anything related to this. I put the bike on its side and I can see a screen in there but it don't look like it should be causing the problem. let me stress this the bolt is not cross threaded or stripped, but I cannot figure this out unless there was a 1/4" crush washer on there that I lost. Any help is appreciated.