Hey Jon
In the spring, I had the same problem as you, even worse. I could'nt get it from Simons, so I had to resque the old rubber. I took an old bicycle tube (from a MTB), fitted it, and glued it all together.
It all works fine.
Hi Jeko.
I did not have any hose rubber to use for a fix, so I went an bought an innertube for a motorcycle. When I cut it to make the fix it struck me that thee fast and easy solution was to use a piece of the hose itself.
The diameter of my hose fit nearly perfect over the ring that holds the original boot. I stuck the piece of hose over the pipe, assembled the linkage and pulled the hose over the ring. Then I fastened it there with a strip and rolled up the excess around the pipe and secured it with another strip.
Not pretty, but it will do the job until I get the boot repaired.