I have a Lincoln Weldanpower Model: WP225G7, Code:9317, Serial #:A1128723. I don't use it too often but when I need it, I need it. It has some rust in the gas tank that keeps stopping up the filter. Lately I spend more time changing the filter than I do welding. I have drained the gas tank and cleaned it with muratic acid which helped for awhile but it rusted back again. There are no leaks in the tank. I would like to buy a new tank but the local welding shop says that they are out of production-any suggestion?

Yep.

Caswell Inc. - Epoxy Gas Tank Sealer (http://www.caswellplating.com/aids/epoxygas.htm)

Try the sealer kiss spoke of.