Duck tape worked, no more leaks into my feeder! Not a permanent fix, but if it lasts this season I'd be delighted.
My bride & I put out 150 lb of AquaMax MVP in three feeders -- they finally had some at feed store. Dock feeder still has some eager biters, but other two are fairly quiet. Still no sign of CNBG, it's all LMB, RBT, and HSB.
Saw eagle, couple of ducks, and four blasted cormorants.