Sorry for my lack of response and thanks for all replies.
@Bugbait : How did I crack the display? In short: Hubris.
Medium length version: I damaged it, outside the case, when removing the hands incompetently. Seeing a risk that Omega would refuse to provide a replacement, I did not want to rock the sinking boat and shout out the embarrassing full story…
The rather long version: I bought this 2nd hand watch a while ago, and I noticed that once in a while, the analog second hand was out of sync with the digital time. Observing more closely, it appeared this would happen when the watch was left in a cooler room, off the wrist. So I put it in the fridge and confirmed that the second hand would stop when the movement had cooled down - always in the same position. My diagnosis was that there was some dirt in the mechanical movement, maybe old lubrication, which would hold up the second hand stepper when cold. Then my hubris kicked in: In the first COVID lockdown, I had started to repair old mechanical watches as a hobby. After some 20 mechanical movements I reasonably successfully disassembled, cleaned, fixed, re-assembled and lubricated, I felt watchmaker enough to strip the 1666, give it a bath, some fresh Moebius 9014 (i.e. 9010 for the fridge) and be done with it. Finding the Omega 1666 technical guide gave me just the boost of confidence to take the movement out. I placed a protective sandwich of stiff material on the display/dial in order to remove the hands, one by one. The second hand, of which I expected most resistance, and minute hand went off fine. To get under the hour hand, I had to remove one layer of my sandwich cushion, and when applying just the tiniest amount of force through my Bergeon hand levers, the pressure was, apparently, enough to crack the display with a very subtle, but expensive sounding “click”. I never made it to the wheel train.
So, I had my Canossa moment, sent the (re-assembled) watch to Omega Germany, and they thankfully didn’t even ask how the display got damaged. They returned the watch to me today, it has a new display (most likely a whole new movement), it passes my fridge test with ease and the whole exercise did cost me EUR 500. Many thanks to Swatch Group Germany for an excellent job and not asking questions. My punishment is well deserved; well - at the end of the day, it would almost certainly have cost exactly the same (flat charge for quartz chronographs) had I just sent in the dirty movement. May this public confession serve as additional penance…
Lesson learned: When removing the hands from a 1666, use something like the Horotec(?) device which lifts them without touching the dial, or perhaps get a laser cut piece of really rigid sheet steel to work on with your Presto tool or hand levers (the widest ones you can find). I am sure Omega work instructions for the X-33, which may or may not exist, would say something like that. The display is ridiculously thin and delicate and when exposed, it will probably crack if you stare at it hard enough.
