OE avs? Run it for a minute on a level surface & take out the metering rods/hangar assy's & take the top off & check float level then take the AP plunger out of the air horn & push it by hand into the AP well & see if it kicks out a good squirt from the nozzle. You can run a screwdriver around the inside of the leather cup to expand it but if it's really worn then as said replace it & get the right dia cup. A good visual & go from there