Trying to source a replacement volume pot for Tivoli Model Two

I have a Tivoli Model Two radio and the volume potentiometer has slowly given up. Just looking at it will cause the audio to drop out of one channel. It's 20 years old, and I could clean the pot, but i'd rather just install a replacement if I can. I've searched, but I can't seem to find a pot like this anywhere. Anyone here have any clues where I can look? The only markings on it are B50k and 5C4. There might be something underneath, not had chance to desolder it from the board yet.

TivoliPot2.jpg

TivoliPot1.jpg