I have an old Homelite C-51 that hasn't run right is a few years, and I'd like to get it back in service again. To shortcut to the end of the story (current state): It starts, idles pretty much OK, and even cuts, but when you pull the trigger the whole way, it's like you're at half throttle, or just not getting much power behind the speed it does generate. So if you're patient, it'll cut 18" logs slowly, but it's definitely missing something. I cleaned / rebuilt the carb and put a new diaphragm in in (the old one was a little crispy, but not awful), adjusted the high and low speed jets, tried cleaning out the fuel line, replaced the pick-up (in tank) filter off the end of the line and even tried it without the filter, but no real luck. It seems like one way or another, it must be short on fuel at higher speeds, but the solution is proving elusive.