I an having a problem with a snapper rear tile rototiller. It has set for several years in a shed. I decided to get it running. Pulled the carb. and serviced it. replaced the pull rope and the spring. Put it back together and got it running. It runs for about a min, and then there is a squealing notice from the pull start mechanism and I have to shut it down. I pulled the housing and the rope is twisted and I can't pull it anymore. I have taken it apart 4 times and every time I put it back together it does the same thing. When I have the housing off, and repair the rope mechanism, it pulls and retracts fine. but when I install it, I have the same problem. Any ideas?