We recently replaced a near 40 year old Blaze King wood insert with a Quadrafire Mt Vernon AE. I installed it myself and it has been working great for about a month. We have put about half a ton of Bear Mountain softwood pellets through it in the last month. This morning we awoke to no fire with an error on the wall unit: "Bad Drop Tube TC". I power cycled, checked connections/wing nut and nothing. pulled the thermocouple and tested it on a meter with a lighter and it was fine. when I put it back in the stove fired right up. The TC was still warm from the test when I powered it back up, maybe that was enough to trick the board into starting? Should I get a new TC to have on hand? I this a regular $5 "K type" that Quadrafire wants $75 for? Any other parts I should stock, I have the extra high temp igniter that came with the stove. Thanks!