The Zip drive's door is flipped up when a disk is inserted, so the disk's rear edge is clearly visible in the drive. You can't miss it. If you see the disk in the drive, is it fully-inserted? If so, have you tried starting up the G4, while holding down the mouse button? As previously mentioned, you may have to remove the faceplate assembly that contains the optical drive's flip-down door and Zip drive bezel. It releases from just inside the front edge of the case by pressing back on (2) release tabs and pivoting it back until it unhooks from the other side. This gives you access to the drive's button or manual eject hole. If your primary concern is the flash of the activity light at startup, you should know that the activity light on all connected drives flashes normally during the POST (Power ON Self Test), whether in a Mac or a PC.