Nothing will get through the felt clunk but some felt clunks can shed small fibers that will plug up the screen. If the screen is properly in place there is no reason to disassemble the carb any further, anything that gets through the screen can go through the carb without causing a problem. Anything in the carb after the screen during original assembly would have caused the problem before now. When you check the screen you have to pull it out of the carb and hold it up to a light, make sure you can see through it clearly not just shadows. The screen can look totaly clean sitting in its hole in the carb yet be completely plugged up.