Hi Todd.
Ok I just tried Thelda on my 512k Ntsc coco 3 using a 6809 chip and it loaded up fine and plays perfectly. Will next test it out on a Pal 512k 6309 equiped machine.
Maybe your copy is faulty Todd. If you want I can send you the images I just used to make 2 disks to test out on my unit.
Laters
Briza