I have a JTP-001 (1-882-481-21)
A quick check to see if a disk is inside is to use something to push back the felt material covering the drive slot. Then you can see by eye if there is a disk in there. If there is, you can open the drive by removing the top metal cover, taking off the magnetic disk and removing the top plastic mechanism cover. These can be left off and you can trigger boot by toggling the arm near the drive entrance.