The metal discs are welch plugs. I usually don't mess with pulling the welch plugs, but some people do, using a pick or small chisel type instrument.
One thing I can tell you is it is a good idea to seal the edge of the welch plug using fingernail polish on the tip of a toothpick, even if you don't pull and replace the plug. Leaking welch plugs can cause erratic running.
Sounds like you'll have solved at least part of your problems when you replace those diaphragms.
Oh, I almost forgot to add - many of those kits come with extra parts because they are meant to cover a range of carbs, so they have the parts for all of them. Usually what you do is match up the old parts from the carb you have with the new ones from the kit and discard the extra parts. You might also want to see if you can get an IPL of the carb you are working on so you can match up the parts and order of assembly. It is easy to get the paerts in the wrong order and the saw won't runh right.
Last edited by dboyd351; 07-18-2013 at 02:48 PM.