I have a problem I have w/ my 1980 Tecumseh HS50 on my Craftsman snowblower. I've installed a new (superceded part # on it) replacement carb on it last year since I've gone thru 3 rebuilds on the old carb, and finally gave up on it (hard starting). With the new carb it starts fine on the 1st pull but I have a problem w/ the engine speed, it surges up & down in the midrange a bit, but more so at high rpms. It seems to "pop" when decelerating from high rpms, too. I don't know how to get rid of any of these problems since it doesn't have any mixture screws. It's been like this since the install. Do you think it might be governor related? I need some tips on setting up the governor to make sure that's not the problem. The spark plug seems to look pretty normal so far, no signs of any extreme lean or rich mixture problems...btw it idles just fine