#2 cylinder always rich and fouled

[Rijko]

I have seen several rebuild kits that have an o-ring on the diaphragm that's a little bit smaller than the original.
And the diaphragm rod almost half a millimeter shorter than original.
So the o-ring never seats nicely, and gas flow does not shut off completely.
An o-ring slightly larger solved that for me.

But a buddy recently solved that by placing 2 small rings in the recess behind the spring, and it held up to now.
( stretching the spring was not sufficient )
Might be worth a try ?