For anyone using Ultralight arms and Ikelite strobes, how do you attach the ULCS ball adapter to the strobe? I have an Ikelite DS200 and the ULCS AD-200 ball adapter that has a flat washer (next to strobe) and a lock washer (next to the adapter). The problem is the lock washer cuts the o-ring on the bottom of the adapter. After I used this set-up once the o-ring was cut clear through. Do you forget the o-ring or the lock washer?