Optical drive not functioning properly after re-installation

I had replaced my optical drive with an SSD, and put the optical in an external enclosure for awhile. I just re-installed the optical drive and now it doesn't pull a disc in at any other time other than when booting up.

The machine sees the OD, and if a disc is inserted on boot-up it will appear on the desktop. But if you eject that disc and attempt to put another in, nothing happens...the disc will not be pulled into the drive.

Is there some sort of switch that might be out of place? Is there any way to repair? or will I just need to get another OD?