I wonder if anyone tries using a good quality RTV sealant on the rubber gasket for the coil?
On my AA, I had some pretty significant rust under the rubber gasket, but I didn't want to to a cut=out and reweld,
so I sandblasted the pitted surface, and LIGHTLY buttered the steel and the matching gasket surface of the old gasket.
I had and still have no leaks..
I shut down my boiler every summer, and only once gave the nuts on the plate a 'tweak' with a wrench.
I think that the good quality RTV [I use Permatex 'Ultra-Black' ] creates a waterproof seal that is NOT dependant on the 'crush'
of the rubber gasket to keep water from migrating between the steel and gasket.
Ive got to believe that with a new, clean steel surface and a new soft rubber gasket, that a THIN coal of Ultra-Black would assure
a waterproof seal for decades.
Just a thought. I don't think any other type of sealant would do the job, they all get hard, except RTV.