My recent post about the 600 Shut-Off Valve raised a trivia question. I would like to know the answer just for my satisfaction. This 57 640 was my dad's tractor that he bought new. The decals under the hood are original. The fuel shut-off decal pictures the shut-off device like a T-Handle like a radiator drain; not a screw or a knob like some. The instructions say "RESERVE - Two turns from either stop." Is a shut-off valve with a reserve the proper one for this tractor, or was the decal left over from the Jubilee? I cannot remember from when I was a 9 year old. I do see any on the market with a reserve.