...they are excellent pedals
They surely are, Alfie. I have six pairs of them and wouldn't part with them for the world. One pair has well over 28,000mi/45,000km and another 32,000mi/51,500km while yet another has nearly twice that. The combination of well-shielded deep-groove Conrad bearings for location and needle/roller bearings for longevity were a winning combination. I have the WTB GreaseGuard-licensed XC Pro version on my tandem.
The bearings themselves are available from bearing-supply houses. Though SunTour once had a tool available, you're on your own if needing to replace them these days. I could turn one down from billet pretty quickly.
Unfortunately, SunTour/Maeda Industries are long out of business, and as I recall MKS/Mikashima actually manufactured the pedals under contract for them. Some MKS parts will substitute, but I think you'll have your best luck using a buttonhead stainless allen bolt and washer. It won't be an exact match, but very close...especially if you replace it's opposite number in the other pedal. I don't recall for sure what it was threaded last time I had one apart, but I think it was M6x1.0. If not, then it was M5x0.8.
They're still available on eBay in various states and also from the JDM (Japanese Domestic Market) Keirin (paramutuel bike racing) sources. I see Hilary Stone has some that might polish up:
http://www.hilarystone.com/pedals.html They have the track cages, but your quill cages could be swapped for them as the body is identical.
Hope this helps.
Best,
Dan.