Here’s the stove and model 9A stand. Dated January 1988. The UK seller has Canadian friends and on a visit some years ago was invited to go camping with them. On his departure for home his generous hosts presented him with brand new examples of the stove and stand they’d been using in camp. He’s used it only occasionally since and as well as the boxed stove (with instruction leaflet) and stand he handed me the remainder of a can of Coleman fuel, so the stove’s never been subjected to pump gasoline additives. A search on CCS and the Coleman Collectors Forum reveals a potential issue of fuel leakage at the control valve, attributed to failed O-ring seals. Mine wasn’t leaking and it’s barely been used, but I was keen to dismantle the valve to examine the components, not least those (two) O-rings. At thirty years old I reasoned that they could be on their way to losing their elasticity and capacity to seal. The valve, generator and fuel/air pickup removed from the fuel tank. I believe Coleman Canada ceased manufacturing products around 1990 but went on assembling parts stocked for a while longer. This 431 must have been one of the last of their manufacturing output and as such, the fuel/air pickup arrangement is known to have reverted to the traditional metal concentric tube construction, the schrader valve in a plastic pickup component having been discontinued by then. In dismantling, the fuel/air pickup tube has to be unscrewed (hexagon flats) first. The ‘innards’ of the valve can then be removed once the control knob’s been removed (pulls off when axial securing screw’s been removed) and the brass end cap (hexagon flats) has been unscrewed - has thread lock sealant on the threads. Line-up (left to right) of the brass component controlling fuel flow; thin hard fibre washer; plunger spring; brass washer; O-ring control spindle shaft seal. The second O-ring is embedded in a circular groove in the end of the fuel control component. There’s been discussion in respect of this seal by others who’ve dismantled the valve that it will have been a circular-section O-ring that’s got flattened in use. I don’t think so. The spring tension on it is enough to make a seal with the flat mating surface in the aluminium valve body. It isn’t so strong to permanently distort the seal, which is still elastic in my example. A square section seal provides more surface contact than a lightly spring-loaded circular section one. I think that was the designer’s intention. A circular section O-ring would probably serve, that said. There’s the sealing surface in the valve body. The generator pricker wire passes through the central hole. The brass fuel/air tube mounting boss protrudes into the cavity and serves as a guide ... ... which engages with the groove milled in the valve component pictured, shown with the generator pricker wire screwed into it. The depth of the groove varies, controlling the in/out position of the fuel/air plunger. The ‘horizontal’ displacement of the groove mirrors the position front-to-back of the component in the valve body, determining start-up; high to low flame and off. Here I’m pointing to the detent position that locates the setting for start-up. This shot illustrates the ‘off’ groove end position (left) and the ‘low’ setting. Bearing in mind that this determines the axial position of that component relevant to the valve body end sealing face. The ‘low’ setting just raises the component and seal away from the valve body end face. On ‘high’ and all flame settings in-between the space is increased over that ‘low’ setting. You can just about see how the seal protrudes out of the component, ensuring a seal. Of course, the axial movement of the component controls the position of the jet pricker rod (and pricker relative to tip orifice). The varying depth of the groove controls the up-down movements of the fuel/air plunger, controlling the proportion of fuel and air. Valve reassembled and generator installed, with thread seal where appropriate. I left off the control knob to facilitate installation of the assembly on the fuel tank. Here’s why I resolved to replace the control knob when the assembly was reinstalled on the font ... access for my adjustable wrench. Large wrench! (18 inch size). Ready to try out on the stove. Both burners fired up. Main burner, max. ... and simmer. Instruction leaflet. Exploded view for the model 431. And the larger 2-burner 432A and 3-burner 433A. Parts list. My conclusions? It’s pleasant to have control through a small arc of rotation of the control knob without the need for a number of turns of the conventional control wheel. The trade-off is reliance on those two seals, which are known to fail. I’m confident I can maintain mine, dismantling of the valve being relatively straightforward. I wouldn’t expect to locate the manufacturer’s spares (seals) but can fabricate square-section equivalents out of viton sheet. Incidentally, the spindle seal being intended to have a square section seams to be confirmed by the square-section groove it mates up against in the valve body end cap.