I used a product from Homedepot, Frost King 1/8" foil and foam duct insulation. It also works well as a sound deadner for vehicle cabs.What foil insulation are you using? Where did you get it?
We've had our 50qt for several years now and it probably wouldn't hurt to crack it open and blow it out. I might as well do these two mods while in in there. ;-)