The igniter has to be removed, before removing pot?
Why remove the pot? Use a Wire wheel on a cordless drill or a small chisel and break up the Carbon.
Why are the holes closing up? I only clean those bottom 8 holes twice a yr. once mid season and at the end of the yr. It really only needs done once a year. At least on mine anyways.
As for pot removal? You will need a new gasket. I didn't use a stock Lytherm gasket. I used a 1/2" style flat gasket. Cut to length, then cemented down to the bottom, now it is reusable, instead of one use, like the factory gasket.
The pot door is hard to open because of Carbon on the flat plate. Open igniter access area, lube linkage, then grind top plate with drill, and all should be well.
I replaced the stock nut and bolt with an actual shoulder bolt. The factory bolt is all threads and can be over tightened. A shoulder bolt can only be tightened to the end of the threads. A trip with the stock bolt to your local hardware, will yield a new bolt, nut, and maybe a washer.
It's been about 3 yrs since I have removed my pot. Looking back, I didn't need to then, but didn't know any better. Plenty of ways of cleaning that bottom plate. It's just some carbon build up. Get a good light, chisel or drill. Go to town.