Something had to blow eventually. Unfortunately these speakers have no part number or manufacturer code on them, and appear to be an uncommon size, 6.25" x 2.25" (159.2mm H x 57.7mm W). They're similar to RCA 234172 speakers and the speakers used in RCA's ColorTrak TVs from the 1980s. Those speakers are rated for 3.2 ohms, 3.5 watts, so they're probably similar in specs, but I'll have another look at the circuit diagram and see if it provides any hints. But new or recent production replacements are almost impossible to find. Nobody seems to produce these. I've queried about having the foam replaced but nobody seems to do that either. Some suggested I use external speakers, but I'm more interested in repairing this TV and keeping it working. It doesn't appear as though a different sized speaker could be modified to fit the cabinet either. There isn't much room to move in there.