Original 56 and 57 wiper motors were vacuum per the parts listing. It also lists an electric motor specifically as a replacement. But even if it were originally electric or replacement electric, it would have a "park" switch inside the motor itself. The dash switch overrides that "park" switch to operate the wipers, and when the dash switch is turned off the "park" switch should interrupt power to the motor as the blades reach the park position.
Sfizio, you'll need to get under the dash and smack that the wiper motor. Percussive maintenance might fix it, but likely it'll need to be repaired or replaced, as the switch contacts may have welded closed or the linkage broken.
BTW, I like your signature. Molto bello!
