Congrats! I own a similar 88 model.
If I was in your position I'd start from the tone generation and then work my way up through the electronics. So to check all the pickups I'd suggest using it without the internal amp for now. Connect the RCA jack from the harp to a guitar amp and you're good to go. Gently tap the magnets for each pickup with a metal screwdriver and you'll hear a loud "thud" for working pickups. This should get you started.
I believe the power amp in this model suffers from cold solder joints on the molex connectors; so this is something to look out for. I certainly had to reflow a number of solder joints in mine.
It seems to me as if there is some corrosion throughout the piano. Make sure that everything makes good contact (this of course starts again with the RCA jack).
If I was in your position I'd start from the tone generation and then work my way up through the electronics. So to check all the pickups I'd suggest using it without the internal amp for now. Connect the RCA jack from the harp to a guitar amp and you're good to go. Gently tap the magnets for each pickup with a metal screwdriver and you'll hear a loud "thud" for working pickups. This should get you started.
I believe the power amp in this model suffers from cold solder joints on the molex connectors; so this is something to look out for. I certainly had to reflow a number of solder joints in mine.
It seems to me as if there is some corrosion throughout the piano. Make sure that everything makes good contact (this of course starts again with the RCA jack).