75 years ago this month, the March 1946 issue of Popular Science showed what you could do with bad tubes. If a tube tested bad for its particular circuit, it was a shame to just throw it away, and you didn’t have to. As pointed out here, unless a tube was completely burnt out, it would probably serve just fine as a rectifier. As shown here, the plate and grids were wired together to form the anode, and the tube could continue for many years serving as a rectifier.