Epap 1000 DE dimmer switch

Hi all, I got hold of an old Epap 1000 DE but the knob for the dimmer switch wasn't on it, so I have no idea what setting the ballast is set at and it keeps turning around fully in both directions so there doesn't seen to be a stopper to say you've hit min or max setting.

I have removed it from the housing to see if there is any way to tell but I cannot see anything to go by.
The only thing I can think of is to fire it up and work it out that way but as the knob has more notches than settings I just don't want to do anything to damage it, the bulb (or me) any help would be greatly appreciated.

What you could do is just disconnect the cable that goes from the ballast to the dimmer switch. When you fire the light up, it will be on its default 1000W setting.