Nigel M, former G1NDM wrote:
"Any suggestions on making or buying a replacement?"

I`ve installed coaxial antennas at VHF which worked well on boats. They
consist of a quarter-wave rod insulated and mounted on a quarter-wave
cylindrical skirt which surrounds the coax feedline. The match is good.
There are no radials to poke eyes. The assembly makes a half-wave
vertical antenna.

At 100 MHz, the wavelength is about 3 meters so the overall length of an
FM broafcast antenna should be about 1.5 meters. You likely can find
such an antenna for sale ready made. If not, it is not difficult to make
your own. The folded dipole made from TV twinlead also works well but
presents a 300-ohm impedance and may not work as well with your DIN
connector. It also requires suspension. The coaxial antenna usually is
equipped with a small mounting pipe surrounding the coax.

Best regards, Richard Harrison, KB5WZI