Well, there's your problem, as I suspected it is a 3 degree taper spindle. You'll have to visit your LBS and get a 2 degree taper spindle. BTW, the 52 refers to the distance between the races and indicates it's indtended for a 68mm shell width.

Unfortunately, getting a correct chainline with a new crankset and spindle can be a bit of trial and error. However, you should be able to get close on the first try. Put the old crankset on the spindle (not installed in the frame) and place a straight edge across the back of the inner chainring. Now measure from the straight edge to a datum point on the spindle, such as the inside edge of the bearing seat. Once you know this measurement, take your new crankset down to the LBS and try spindles until you find one closest to this measurement.