Problematic Macintosh 512K 800K Disk Drive

[SilverStreaks]

I bought a Macintosh 512K that came upgraded with the newer disk drive and ROM chips. I'm able to boot just fine off of the external 400k drive. However, the internal drive is problematic. Out of the many time's I've tried to boot, it only worked twice, the second being kind of glitchy. Otherwise, I either get an x or a happy mac, and then the disk promptly ejects. I am also unable to successfully format any disks. The drive head moves all the way down, and then fails and ejects about halfway back. This happens with both 400k and 800k formatting. The resulting disks are unable to be read by my 3400c, which on the other hand is able to read disks otherwise formatted by the external drive. I have already cleaned the drive heads, so I don't believe that's the issue. The disks themselves seem fine and reliable as well.

Any ideas?

 

[SilverStreaks]

Update: was able to get the drive to initialize disks after adjusting the homing sensor. However, these disks are unreadable by my 3400c as well as the external disk drive.

Upon proceeding to adjust the stepper motor, I accidentally shorted something. The drive continued to work perfectly for a while but then encountered issues.

Will have to fix this before proceeding.