We are new owners of an Encore 2550 stove that came with the house we just moved into, and we're not sure exactly how old the stove is. We partially disassembled and cleaned it in order to replace the catalytic combustor, the refractory assembly, the secondary heat probe and various gaskets. We see in the owner's manual (which we are not sure came with this exact stove) that there is a thermostat assembly behind the right air plate to control the primary air vent. When we had the stove apart we didn't see one of these. Given the general condition of the stove, we wouldn't be surprised if the previous owner had removed it. But we're also wondering: Has this part ALWAYS been in the Encore 2550, or was it added in later (1997 and after) models?