Here we go...
Here you can see all of the components, minus the roll pin.
You can see one of the wear grooves I was walking about.
I drilled out the welch plug and there was some kind of powder behind it, kind of like saw dust. I cleared out some of the powder and drilled a bit deeper, I hit the shaft almost instantly.
The gear was in very good shape and is VERY securely attached.
That's the gear end of the casting after cutting it in half.
The shaft end sits against that, there's no washers or anything.
The one and only washer. It did have some wear but not a lot. It goes between the gear and casting.
The casting is very easy to cut through, but the shaft is incredibly hard (giggity) to cut through. The first hack saw blade broke in half shortly after hitting the shaft, the second had pretty much no teeth left by the time I was done. My arm hurts a little from it. I was gonna give up and use the angle grinder if I broke the other blade.
You can insert a hex socket into the end of the shaft, that might be a good way of holding it in place while you remove the gear. My first idea was to lock the gear between two blocks of wood in a vise and turn it with a hex socket, it didn't work because the gear chews through the wood and turns. I also tried hammering the shaft out but that didn't move it.