Thanks Jon. Do you know when that "fix" was developed? We agree, it can only make things worse.
But here is what I think is a good solution. Sometimes when my mind relaxes, interesting visions appear. And this afternoon I was looking at another Carter YF which suffered this same warpage. No funny little gasket there, but the screws holding the diaphragm bonnet were too tight. And in this one there were some casting irregularities that caused one edge of the bonnet to have a high lip.
Get a 1 inch Forstner type bit and a known flat piece of wood. Preferably hard wood, but I used a piece of scrap poplar which isn't very hard but nice and flat. Drill a hole about 1/4 inch deep as you see I've done in the first image below. Now get two pieces of sandpaper. I used wet/dry, but you probably could use other types. The first one...and here I used 220...cut so that a bit hangs over each edge of your wood and use a box cutter to cut out the hole in the middle. Now holding the paper on, take your bonnet and rotate it in the hole, pressing down on two opposing corners and trading positions as you do so that you don't just put pressure on two points. Do this until you see the surface is looking smooth. Now repeat using fine sandpaper. I used 600 grit for the second pass. And now you have a surface that is enviably flat and smooth. As in the second image. I thought about Red Green while doing this, fyi. Now clean any abrasive or metal particles out very thoroughly and you're set.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
