My wifes 250 ninja would start with the choke on and die when you turned off the choke or gave it gas. Since this seems to be a common issue I removed the carbs. They looked very clean but every post I've seen says CLEAN THE CARBS. Removed the float bowls and the main jets cleaned thoroughly. Turned upside down and filled the top with cleaner, shook slightly and dumped, first time it came out with a green tint to it, next time less green more yellow. So not knowing what I was getting mysflf into I removed the cover of the vacuum piston. So now that I have cleaned it.... how do I get the rubber to stay in the groove long enough to put the cover back on?