The springs have a damping sponge inside them. They should be left in.
Operational problems with these turntables after 40 years is common.
There could be oxidation on the operating buttons. Capacitors on the main board may be out of tolerance. Sometimes there are faulty transistors. Mechanical adjustments need to be made per the service manual. Sensor lamps might need replacing.
You can look up a lot of information about servicing them here.
-sonavor
