need a little help i am working on a cart at work it is a 2005 model txt with the 295 robins it was running very rough when it came into the shop. the first thing i checked was the firing of the plugs it has good fire but 1 plug was dry and the other wet . next i checked the valves made some very minor adjustments and started again still had the same problem. i started to take a look at the carb. next i found the black knob at the engine side of the carb. had apparently either vibrated all the way to the left or either someone had tinkered with it any way when i just touched it it popped off and looked like the shaft was broken. question is if this was closed off would it cause this problem if not what should i check next.