Hmmm.... I can only guess what oex meant. Switching the polarity of the speaker wire fixed the problem. How did he conclude from that that there's a damaged and shorted wire?

I'm guessing here, but try this. Disconnect the speaker wire from the back of the Cav, like you did before, but instead of switching them, twist them together and leave them temporarily disconnected from the Cav. Then, go to the other end of the cable, where it's connected to the speaker. Remove the wires from the back of the speaker, and connect them to the leads of the ohmeter. If the resistance is too high, that indicates a poor connection somewhere.

This is close to the time of year when the weather turns cold. When this happens, the roof rats around here look for shelter. They'll gravitate towards places that are relatively warm, and have a food supply. Like the bird food we used to store in our garage. Rats chewed hoses on the washing machine, wires on my water softener, and hoses and wires on both of our vehicles. Sometimes we'd see a dead rat in the driveway. I'm guessing they were poisoned by the antifreeze in the cars. Our little Yorkie kept trying to tell us about this problem, but we didn't listen. We had to learn the hard way.

Look for signs of rat droppings. Set rat traps. Peanut butter makes good bait.