Organs built after 1978? tend to have keying IC's. These can go bad, particularly if they are of MOS construction. (CMOS, PMOS, NMOS). ICs with part numbers like CD4016B or CD4052B are commercially available and cheap. I helped a guy with a Conn that had a custom MOS IC that both picked up the key contacts and released the data in serial format, so that was a single source part (bankrupt Conn or receivers or scrappers).
If you search organforum:gulbransen you'll see post by our gulbransen expert. He will know your production year and might have the schematics. Use a commercial search engine, the search within the forum finds every post with any word you type in it. You can also look at Jan Giradot's master list of organs produced, to look up your model.
If your organ is pre 1979, you might have a key contact stuck on somehow. That could happen to a later one too, but it is rare on either. Some organs used semiconductor diode keying and these can be defective.