As you can see, the computer must be able to respond very quickly, when you consider all the notes that can be played simultaneously, from so many stops. Each stop tablet on older organs controls several switch contacts. Most technicians never lubricate the tablet mechanisms , but they will operate much more smoothly when this is done. The electrical contacts oxidize , requiring periodic cleaning. Motors require periodic lubrication and removal of dust that tends to clog the cooling vents.
Belts gradually stretch, requiring periodic adjustment and eventual replacement.
Older organs have electron tubes in them. The life of a tube will be lengthened if the layer of dust is removed. Dust acts as an insulator, holding the heat inside the tube. Tube pins and sockets need periodic cleaning, too. Many problems in tube organs are related to oxidized high-voltage pins and sockets, and switch contacts.