I was gonna say the TX too but it's really just wire wrapped around a piece of metal. Not a lot to go bad there. Is it possible that one of the little wires to it has a bad connection? That would be easy to fix, and potentially without replacement.
If you need a new one, Edcor makes 600:600 TXes that are very well-regarded and affordable. I'd think a Cinemag would be closest to the original, and if you really need that "warm authentic vintage sound" leave some magnet wire out on a rainy day then re-wind the TX with it.