I also have a 500, 501, and 502 using a 5.25 and a 3.5 inch drive. However, I want my 3.5 to be Drive 0. I have been working on this for a long time messing with twisting 12,13,14 Removing pins, Trying to solder the jumper on floppy drives. So far no luck. Have you or anyone had luck...