Many a time I have used a sharp razor blade to remove the scale from a port hole window glass. If you pm me your address I will send you a drop in set of Teflon gaskets.
I sent a set out to Montana earlier this week in an envelope, waiting to see if they make the trip with cheap postage. What thickness are you using? I use 0.025” as suggested by Rog, but haven’t bought any since 2008 and am having trouble finding more in that size...
I use 0.030 , I prefer that thickness as it brings the ring out more even with the front of the boiler. I have sent many a gasket set through the mail with 0 issues , I just tape them in rows so they don't gather in the corners.