They’re Platter Dots!
These are a useful indicator of how efficiently your motor is running. As the platter spins, a strobe light flashes and lights up the dots. If the motor is functioning properly then you should be able to make out the dots even as the platter spins; each row of dots should appear frozen at certain pitch settings. Watch the video for more guidance on this. If they aren’t frozen then it can mean that your motor or pitch control needs servicing.
Credit: thevinylfactory.com
