Rubber knob off back of radio

The radio on my Defender is supposed to have a rubber ‘knob’ on the stud sticking out of the back of it that locates in the frame in the dash and supports the weight of the radio when it slides into its ‘cage’.

On my radio the knob is missing and sometime in the past, it’s broken the panel it sits in. I’ve got a new panel. (£40 ) but I don’t want to fit it and have it break in the same way the first one has so I wondered if anyone’s got an old radio kicking around that I can scrounge the rubber knob/button thing off the back of?

Cut and shape a bit of rubber/neoprene tubing, simples

If I only had a bit the right size...

Good idea though and probably easier to source. It’s quite small and the ones I’ve seen before are quite tough so not completely straightforward. Neoprene tubing might be ok?

Otherwise I’ll try a local car radio installer (we haven’t got one nearby but next time I’m in Guildford I’ll go and poke around.)