Small Engines (Lawn Mowers, etc.): engines starts, wont run; fuel filter???, fuel filter, recess

Question
Tecumsah engine, gets spark but not fuel.  I've followed the advise of others and cleaned the carb twice.  Blown carb cleaner through all of the jets.  Carb appears to be clean but engine will only run if I provide carb cleaner directly into intake while running (not drawing gas itself).  My question: there is a small "circle" in the roof of the carb (next to the float needle) that is rusted.  The diameter is just smaller than a dime. The rest of the carb body is aluminum and shows no rust.  This circle appears to be a piece of metal that can be removed but I've not touched in fear of doing harm.  Is this some type of fuel filter that may be preventing gas from feeding the intake?  When I press the primer button it appears to be drawing fuel through a small slit in the recess that holds this rusted part.  

Answer
Hi Marty,

The welch plug/disk shouldn't have to be removed but if you have tried all else, you could pry it out and look behind it for debris.  The next step would be replacing the carb.   Some times they just can't be repaired.  Double check the carb to make sure you haven't missed any clogged small opening.

Let me know how you make out.
Michael