Turn the Sony VP-7020 U-Matic player off and disconnect the power cable from the surge protector or wall outlet.
Unplug all of the cabling connecting your Sony VP-7020 to other audio and video devices and monitors. Unplug the cabling on the peripheral equipment side as well. Make a note of how your cabling is connected if you are not sure how to reassemble your setup later.
Test your audio and video cabling with a multipurpose cable tester that will test cables with different connection types. All cable testers are different and the procedure for testing different connection styles is often different. Check your owner's manual if you are unsure of how to test properly using your cable tester. Replace any cabling found to be faulty with new, working cable and test your setup again.
Check the power cable connecting your Sony VP-7020 with a voltmeter, which tests voltage to make sure a cable is working properly. Voltmeters can be found in hardware stores as well as electronics supply stores. All voltmeters work differently, so you should read your owner's manual to learn how to obtain a proper voltage reading for a power cable. Replace a faulty power cable with the exact same type of power cable. Faulty power cables are often responsible for intermittent function and certain playback problems.