. . . with any of the five cal 39 G O's I have personal experience with, including the Senator up-and-down which I owned for over four years. The problem could be in the planetary gear train for the power reserve indicator or insufficient winding, but I rather doubt it's directly related to the rotor. I would suggest using a winder (set counter-clockwise at the lowest possible rate) to see if it's just a matter of providing enough energy to the mainspring, and rasing the turn rate if the lowest setting doesn't cut it. If the power reserve indicator still refuses to budge beyond the half-way point but does so with manual winding, then perhaps a call to the G O service department is in order. Cordially, Art