They truly never need tuning . Many organ sales people have lied to their customers, stating that the organs they sell never need tuning. But Tonewheel Hammonds really do not deviate from the correct frequencies. All of the spinning disks are mechanically linked to the synchronous motor by gears. Periodic lubrication is essential to the life of a Hammond tonewheel generator organ.
Fresh oil keeps all of the brass bushings and motor bearings from wearing out or seizing.
Hammond recommends annual lubrication for most of the Tonewheel models, quarterly for some. Neglecting the annual lubrication is like neglecting your car's oil change. Rebuilding the generators is very costly, usually more than the value of the organ. I have successfully extended the life of screeching organs for several more years using Teflon-based chemicals. I still have some used tonewheel generator units available, too.