Rubber Components
Your record changer is probably a Voice of Music (VM) built unit. As these units age the rubber motor grommets that were designed to isolate the motor from the chassis harden and no longer do their job. Additionally, the rubber drive wheel that acts as an interface between the motor shaft and the platter is probably hard as well. When these two units age and harden you will hear a great deal of mechanical noise through your speakers as records are played.
The good news is that replacement parts are still available. A good source for information on VM products and their repair is thevoiceofmusic.com
I hope this helps.
Bill