Of course you will need to know how to handle the ciphers and regulate the mechanics of the organ. You will also need to know how to tune the pipes or the stops that get out of tune easily, such as reeds and stopped flutes. So get some basic tools for maintaining the instrument such as a screwdriver.
But I strongly recommend that you get help from an expert organ builder who has lots of experience and who can teach you what you need to know. Trying to learn it on your own might seem like an easy way out but it might be pretty dangerous for the instrument. If you have no experience in maintaining an instrument and you are blindly learning from your own mistakes, you can make mistakes in the situations that can make damage to the organ.
And damages can be quite costly especially if it is a historic instrument which is protected by the state. And even an organ builder who advises you and teaches you how to maintain it, has to have formal and official qualifications to work with historical instruments.
But don’t be afraid to open the panels of the façade and to look inside the organ and see how it functions but dry not to cause the damage by touching things in a way that it’s dangerous for the organ.
Writing introduction for the tomorrow's SOP Podcast #1 with the organ builder Gene Bedient. Writing fingering and pedaling for the Toccata by Charles-Marie Widor. Editing Part 3 of Sonata No. 1 by Teisutis Makačinas. Assisting Gianluigi Spaziani at his recital „Vater unser im Himmelreich“ at VU St. John's church. Transposing hymn setting "Jesus Sinners Doth Receive". Practicing 12 Technical Polyphonic and Rhythmic Studies Op. 125 by Oreste Ravanello and adapting them to fit Dominant 7th chords and their inversions. Practicing "Virtuoso Pianist" by Hanon in C Ionian mode (only white keys). Playing Office No. 34 from “L’Orgue Mystique” by Charles Tournemire. Improvising with Dominant 7th chords and their inversions. Composing "A Morning in the Countryside". Reading "A Beautiful Constraint".