Top comes off then there may be screws or latches at the side that let the keyboards rotate up. Wurlitzers tend to rotate the keyboards up out of the way, but that was in 1966, haven't worked on a 1978 model. I think this shows that rock is certainly exerting an influence in. If the dc voltage to the keyer IC does go up & down from the 'bad keys' just like the good keys, then either the keyer IC is bad, or else as I said in the beginning, faulty power supplies are just bad enough to make one IC not work but the other ones do. 'Look at the way Wurlitzer has incorporated an Orbit III synthesizer into its new organ. It has a basic envelope that includes attack and sustain, a filter of sorts (called 'wah-wah' - guess what. It was included as the third manual on many different Wurlitzer home organ models since its introduction in 1971 (models 4037, 4373, 4573, 555 and others). You need an alligator clip lead for the negative probe anyway to nail that to analog ground. The Orbit III is an unusual, but not at all rare, basic monophonic synthesizer. Available from newark, mouser, digikey, Fry's, etc. It is best to use a Pamona 'dip clip' and a pamona 'grabber' to check actual leads on the IC. It is best to check dc voltage on leaded parts (like resistors) that go to the IC instead of touching the IC itself.

You can prove or disprove this theory with a voltmeter. Upper and Lower Keyboards: 5 octaves each. Some of them may not work, Ie the Dc voltage may be in the 'note on' state all the time. Some of them work, ie the DC voltage comes and goes as you put the key down and let it up. If there are keying IC's, then probably DC voltage comes from the keys to the gate controls. You can check the key contacts with a voltmeter, instead of taking everything apart first.

Wurlitzer orbit synthesizer organ