I just mounted (out of the plastic bag) a new AM carb for a Stihl MS 250 and it works perfectly. It's amazing how quality can vary from one supplier to the next. It's also amazing how PioneerGuy600 can fix about anything. My hat's off to you.I took a bad AM carb a customer had me change it out for an OEM one. The Am one had metallic crud blocking two of the feed drillings/passages that no amount of US vibratory cleaning could dislodge.Carbs were clean as possible so for just curiosity sake I got out the jet drill case and tried chasing the passages, it took a fair bit of time turning the pin vise but once the jet drill made its way to the venturi and after blowing with comp air and carb cleaner through the passages that carb has worked fine on a neighbors saw for the last two seasons. It seems the Am manufacturers take a few shortcuts in their cleanup process.
BTW, sliding on a new carb into an MS250 is rather tricky. Not much clearance anywhere, especially between the fuel hose and the bottom of the carb. It's a squeeze to say the least. I remember not having that difficulty when I changed out the carb on my 361.