I have a 2001 425 I rehabbed since it was quite a rusty thing when I brought it home. It seems to run well and buzz right along. I changed all the fluids, plugs, new fuel lines, cleaned it up really well with replacement body panels and the like. Then I picked up a 54" mower for it, its in great shape, changed the fluid in the gearbox, new blades did some other nit-pick things to it. Installed it on my tractor and went to fire it up. Tractor stalls, figure I need more throttle, tractor stalls, hmm....one more time, it kicks the belt off the mower. Now I am frustrated. Put it back together, go to start the pto again and give the tractor some choke and it coughs spits and finally takes off. I have run seafoam through the fuel, fresh fuel, different octane, and it still will kill the tractor if I don't choke it. Is this a common issue or do I need to have the carb cleaned by someone with a ultrasonic cleaner? I would hate to have to replace it since it is probably very expensive. Any advice would be helpful.