honsetly ever since i used it for 2 weeks my cermic plate has been so black, and loaded so frequently i cant see it glow anymore. i boiled it and stuff like a week ago.
This is very typical (subject to the concentrate). Depending on how deep and thick it is, sometimes a 20/20/20 burn will help, but it's only cosmetic.
Switches can (and have) failed for a number of reasons. Hopefully we're not looking at a fresh set of problem switches (as has happened) but I doubt that based on reported timing. They can also fail because the switch itself isn't screwed solidly into the SS ring that makes the end cap. The switch body and ring are different materials and have been known to work loose. Anyway, always good to be sure it's really well threaded in. Also possibles are the connections to the switch for the spring and ground strap, both buried under epoxy and out of reach. Spring tension can also be an issue, some batteries are shorter than others and even with a good fit a solid bump on the tail can jam the spring and get it to collapse, so I'd also suggest checking for proper spring tension before blaming the switch itself.
At the kind of power levels we're running (about 4 Amps worst case), dicey contact issues often can be found by the heat they generate. Look for things getting hot sooner or more than before. A trick often used in such cases is to put the whole thing in the freezer, until it frosts up solidly, then fire it up and watch to see what thaws first. This is what led me to a ground strap connection problem a while ago.
The ball of foil test is the definitive test for switch problems as an assembly. If you get improved performance with it you can drop your search plans elsewhere.
OF