Has it really been over a year and a half? Feels like last week... Anyway, I just wanted to follow up this thread with perhaps one last update on that big huge pile of Apple ][ stuff. After a long time of trying to troubleshoot the problem-prone ADT Pro audio client, I have finally figured it all out and have been writing games to floppy disks. I even got a nice new desk to put the Apple ][ on, along with a 2600 Jr.
Concerning ADT Pro, I eventually discovered that two of the biggest problems were the audio levels on the host computer (not low enough) and some disk images were in fact bad. They would either consistently fail transfering at specific blocks, or they wouldn't boot after a successful writing.
I also backed up that copy of Spyhunter that was mentioned earlier. I tried out the disk image in an emulator and it works fine, aside from the graphic glitching on the semi, which are there on the original floppy too.
http://www.mediafire.com/?549hgh9odluwx9k
In short, I think this thread had a happy ending after all. The Apple ][ works great, I repaired the cut cord on that custom-looking joystick, but still have to replace the microswitches in the joystick (one is broken) and I've even managed to get some games written to floppy disks.
There's just one small issue right now though. I am unable to find clean dumps of Montezuma's Revenge and Apple Cider Spider. Every copy I've downloaded online refuses to transfer completely or boot. Can somebody help me out?