This guy is on EBay and carries new idlers for a few different models.
There is a vendor in Italy that makes idlers for a few different models too.
I asked him for an Idler on a Presto.
A LOT of the idler parts are interchangeable with Rek-o-kut, Empire, Russco, QRK, Sparta, 412 Fairchild, Harris, Gates and Presto.
I'll hunt that up for you too, he use to be on EBay, but I knew him before there was an internet.. His son now I think, maybe a grandson. He would be about 550 years old now, he was 500 years old 50 years ago. :-)
I had 2 16" cutters one Presto and one Rek-o-Nut that I keep going for 20+ years.. I just liked my Fairchild 750 better
I had 25 made for rim drive Russcos when there were no CnC that I knew of. I paid 20.00 each and the guy turned all of them out in 3 or 4 night after work for me.. He set them up for O-Rings and you just had to find a quiet piece of rope, index, glue and polish the rope. I used BR, Silicone, natural rubber, neoprene, and Nitrile. Softer silicone rope is still my favorite.
There is a guy here on AG that is a machinist. billwojo PM him see what he thinks? He has a few neat little rim drive projects going..
Russco and Gates I think.. Maybe Harris..
Don't we all :-)