Luxman MQ68c Amp - Trim Potentiomenters

I'm testing some old equipment that has been in the family for decades, and noticed that several of the trim potentiometers inside the Luxman MQ68c amplifier have broken apart. They were Helitrim model 91 pots - some 5k and some 10k. I've done a bit of research and it looks like these are no longer manufactured. Ebay has some Helitrim trimpots but not the specific values I need. Obv. I could replace with another brand etc but would rather use the original type (which are nice because they have long leads...)

Anyone have any good resources for vintage electronic components?

Thank You