The rubber seal probably wasn't in the 964s or 965s, but I add it when I rebuild one. The problem with that seal is you must have the metal collar to sit atop it. The purpose of it is to prevent gas from sloshing up and running down the diaphragm arm (the lifter arm)...which will happen. If you don't have that metal collar, you can make one but it is fiddly work. It must be made of very thin aluminum or brass and is just a shade larger than the rubber seal piece but matching it in shape. You don't need to buy a rebuildable carb and you won't find a cheap one unless you're really lucky. As Lee said you have the arm upside down. Some will call that arm the lifter link. I have no idea what Mike's calls it...I have no comment to make about Mike's here. Everyone is entitled to their opinion and can deal with who they want, after all.
Please see the attached...General diagram of YF. The scan in jpeg format is too large to be attached. This is a pdf and I hope you can save & open it. I have scads of images of work done on the YF carburetors...maybe 200 or more.
Part number 28 on this diagram is the pump lifter link. Atop that sits the metering rod arm--part number 25. The metering rod clip will sit flat on early models and at a slight angle on later models. The diagram I showed you earlier shows this clearly. There is a metering rod clip (part 26) which I call the spring. One end of it fits through a tiny hole in the metering rod clip and the spring part fits on the round protrusion on that clip and then it wraps around the metering rod. You can see this in the image below. Once you get this in your mind, it is very simple. Take a look and let us know what is confusing you.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
