yeah it's a smaller hole then the mera one. what I did was measured the largest and smallest relevant areas of the motor spindle where it ataches to the wiper, then drilled the punto one through at the smallest sixe needed, then going up in .5mm steps made it angled sinilar to the splined section of the motor, to ensure it clamped teh splines tightly and properly.
I'm crap at explaining stuff, this might not make sense until you see the motor/wiper in pieces.
oh and BIG tid, THOROUGHLY clean the splines on the motor spindle before putting the new wiper on. might take a little time, but it's VERY worth it, as you could one day find the motor spinning and the wiper hanging over your number plate.