Did yours suffer physical damage or to much power? I repaired a T27 that I popped. After unsoldering the wires, the diaphram can be pried off. Mine, from 1979 had 2 locator pins for easy re-assembly. Mine burned out a small section of wire that goes from the VC to the flat portion after the suspension ring. I very carefully peeled off I coil of wire from the VC side, scrapped it clean and resoldered. I could not hear any difference although it had to have some effect.
maybe this can get you going till you find a replacement.