I purchased my 8520 back in September, and it was missing all of the quill fine feed gears. I purchased and tonight just received gears from Stock Drive Products, sdp-si.com . Here is what I purchased:
24DP12T, 3 inch long pinion wire stock, #A1C29-N23012, $20.44
32DP12T, 1 foot long pinion wire stock, #A1C 9-N321012, $19.42
32DP32T, 3/16 wide, 3/8" bore, #A1C1-N32032, $10.08
32DP48T, 3/16 wide, 5/16" bore, #A1C-N32048, $13.95
They may require some custom shafts to make it all work, but I think it's do-able. I probably won't get to it for a few months, as I am quite busy on a remodel project at home and will be travelling quite a bit for work over the next couple of months. Anyway, just wanted to share some info on this source for gears.