[Hanuman]

Electrical/electronic, I’d say. It might settle down. It may occasionally play up. Drive by ear, and experience, and set this all aside for a late spring revisit.

Most of these systems are reliant on electronic senders and signal cables, these days. Long term storage of anything electrical can lead to simple tarnishing of connections. Automotive circuit boards are of a pretty low level of integrity by comparison with the electronics in black boxes that you and I are more accustomed too. Thus reliability is lower. And nothing electronic likes being shut down and unsympathetically stored for any period of time.

Even the famed quattro has a small stepper motor involved, and a circuit that occasionally goes faulty, and burns out entirely one of the more expensive components- the digi dash.
Faults with the odometer can easily be the gearbox sender, it’s local connection. The connection at the instrument cluster. Solder dry joints where components and interconnects… connect. An erratic signal to the chip that drives the stepper motor that advances the gear. Or disturb the line resistances. Some of the same signal sources that result in static, or erratic needle behaviour.