I have a CLD-D406 that functions well. It is just that it shows some odd behavior that you can only see when the top is off. On power up or when there is no LD on the tray, the laser pickup moves to the center of where an LD would be. It then starts moving back and forth horizontally. The movement could be called "hunting". The range of movement is maybe 1/16'th of an inch. Though not much, the pickup makes a faint clicking noise when it reverses direction. The noise can be heard faintly when the cover is on the player. The "hunting" seems to stop when an LD is on the tray and the player plays an LD perfectly. The "hunting" is hard to see when an LD is on tray, however.

Is there a cure for this "hunting" or should I just not worry about? Maybe, I should worry about it when the player stops working?

I think this is just the player reading the table of contents to notice its an LD, CD etc.
But this is only when you put the disc in before playing?

Probably the gray motor holder holding the pickup motor onto the laser assembly. If you look thru the holes at the gears on the side the gears need to turn only when pushing it by hand or just watching it operate. If they jump up and down a little the pins that hold the two side gears in place a broke. You need the improved black colored motor holder used in the DVL series. But the is no longer available. Have to take them from a parts DVL unit now.

Yes. There does not have to be an LD on the tray and the pickup still moves. The time between "clicks" is about 1 second. I cannot test a CD as the player will not release the CD onto the tray when the eject is pressed. You then have to remove the top to get at the CD and get it to drop.