A Landeron 251 movement is a chronograph without the usual push-buttons to operate it. The movement is operated entirely through the crown. For the chronograph, this means starting, stopping and resetting the time measurements. A 45-minute totalizer is also provided. Of course, the same crown is also used to set the hands correctly and to wind the movement.
It took a lot of time to repair this movement due to the scarcity of parts. For the chronograph's minute counter, we had to find a new pair of wheels as they had broken off the axle. Also the adjustment of this movement was a difficult part of the repair because the eccentric screws were twisted.