Sea Ray

First time to winterize my 1998 290 Sundancer, single engine.  Hardware store person said NOT to run RV antifreeze through the water heater as it would ruin the electrical heating element.  I could not find this anywhere else, so I'm asking if anyone...

About 1/2 bottle of red wine tipped over on the forward berth mattress.  Any good ideas about cleaning the foam mattress and cover?Thanks.

I recently purchased a '98 Sundancer 290, and the back light system for the rocker switches and instrument panel do not work.  I replaced the dimmer dial, still nothing.  The source of light seems to be some kind of foil strips with wire leads, cover...