I thought of the floats as well and checked them using the tube method out of the service manual, I'm not used to doing it that way, I've always measured from the bowl surface. Anyways, the level was good. As far as something missing, it's certainly a possibility. I don't know what it could be, I've looked at the parts breakdown quite a bit because while rebuilding them, I had a couple of mysterious parts left over. One was a small aluminum piece, which was the main nozzle, which I've never seen them fall out before, and I only had one so I had to order one for the second carb. The other mysteries piece was a copper ring, which I had 2 of those and I guessed that fit around the main nozzle, it was the perfect size. Some parts diagrams didn't even show the main nozzles and it isn't shown in the service manual, but I did finally find it, however, I don't think I ever found the copper rings.
So all that being said, it certainly is possible, something is missing or wrong, I just don't know what it could be.
I also talked to the owner saturday, told him all that was going on so far, he mentioned that when this happened, it seemed like the exhaust sounded louder before this happened, so now im wondering if the exhaust might be plugged?