If this is still a conventional classic system, a spiral bound wire runs inside an aluminium tube. Under each wiper a wiper gearbox is clamped by two fasteners over the tube, which has flared ends. Inside the gearbox is a toothed gear which engages with the spiral bound wire. The wire moves inside the tube, and is driven by a crank wheel attached to the motor, usually using a pin into a hole on the end of the spiral bound wire. If the wipers can be moved in synch, and the motor works independently then the crank wheel is not connected to the wire, or not connected to the motor.
Thankfully this system is usually reliable and on the Trads is on the bulkhead. This assumes that Morgan have not used a more modern alternative!