I've dismantled a few K-jet fuel distributers from Saabs, to see why they weren't working as they should.

It's usually rust on the spacer plate, or in the fuel metering slots.

As far as I am aware, there is no rebuild kits available for any of them. The castings are bolted to the spacer plate with no gaskets. The machined surfaces against the spacer plate seal when everything is both new and extremely clean, and somehow seal against it.

I hate to say it, but I think you're in for a new one. Yea, I know that Bosch is damn proud of those things.