What could be wrong with my Toshiba light meter?

Many times the corrosion will follow up a wire inside the insulation, try replacing the wires to the battery holder--requires pretty good soldering skills. I like the Sekonic incident light meters, use no batteries or the Gossen Luna Pro F or SBC. Note most new meters will run every bit of your budget try to find a good used one from a reputable camera store, if you can have only one meter (and I own more than one) I would get a Luna Pro F, it has system accessories and measures both continuous light and flash.