you can take a Q tip and a cordless drill and clean the seat. put  polish on your finger rub it into the q tip. you dont want any excess polish on it.
then put it in there and give it a few good revs on the drill. this will help clean the area so you have a good seal. and when you put seat valve back in put some of the oil for your gas on the rubber o-ring to help lube it up. but you need to get floats set right and sounds like you need new reeds. this will be your hesitation fix. i hold reed cage up to light if you see light coming through they are bad.