[200q20v] UFO rotors turned, violent pulsing follows - Help!

[Steve Bednarski]

I found a shop on the East coast that can turn UFO rotors.  My 1991 200TQ
suffered from a minor pulsing upon braking, so I decided to have the UFO
rotors turned at this shop.  I have dealt with this shop previously and they
seem quite competent.  In any case, after the rotors were turned, I
remounted them and re-used the old pads (which had about half their life
remaining).  Now the car pulses violently when braking.  Could it be that I
need to change the pads at the same time?

Any thoughts on how to proceed?

Steve Bednarski