No idea how old the carb is, I got it on ebay. I don't think it was ever used but it could have been sitting around for years. A stiff diaphram would explain why it wouldn't pump gas up to the carb at all the other day, right? But it did work when it was on the bench. The carb screws are good and tight and I'm pretty sure the fuel line is attached to the right nipple on the carb. There are two brass tubes coming out the same side of the carb, one I have plugged off because I think it was the return line to the tank (although this carb doesn't have a primer bulb?) and the other is closest to the diaphram side of the carb and I have the line from the tank attached to that one. It wouldn't work at all if I had them reversed would it?