So I found the manufacturer of the rheostat, K B. The part number is KBMS-13BV, which is a special build (not available from most KB distributors). I found several distributors for KB products, but one I spoke with today told me that the details of that model is hidden so they can't cross it one of the many others they have. I did find a couple of potential sources, on in IL and another in CA, that might sell them or have the specs so they can cross it to something they stock. I'll let you know what I find, maybe I should buy 20 and stock them for other Quadrafire customers!