Hi Ed

Yes! I think it is the same problem.
On the 2020 the riser has a cone inside it so that the water from the heat exchanger is not squirted directly into the exahust. The water spreads around the cone and is then pulled into the exhaust flow by the exhaust pressure.

My risers have been full with rock hard carbon deposits which have also got into the cone. I think it would be impossible to do any “rodding” inside the cone as it is a tight fit. I have heard of the soaking solution but I am doubtful that it would work on the rock hard carbon.

I am going to talk to a stainless steel fabricator to see it is may be worthwhile having something made where the other shell can screw off exposing the cone.

Will keep you informed.