Rollaway garage door?

The control unit has packed up on my rollshutter garage door and it's a pain winding it up by hand. I can't find out what the voltage of the motor is without taking the roll shutter down and it's a pig of a job. Any one know what the voltage could be. Nothing in the control box even on the transformer indicates the voltage out put to the motor. I can't afford the £250 +call out the installlers want so am thinking of putting it on a two way switch control unit.
My arms are getting tired now winding it up and down.