Shipbuilders sometimes do run into problems with subcontractors shipping late, defective, or wrong parts.
When Stewart Bale arrived to do the formal, pre-maiden voyage photos of the Queen Mary in 1936, the lampshades for the Main Lounge had not arrived - so the photographer carefully arranged spare ornamental glass from the dome in such a way that the floor lamps *appeared* finished, but of course, were not.
That being said, I never bought into the missing clock story on the Titanic. First the evidence sounds slim. I asked about this a few years ago, and it boiled down to a "Somebody says" story.
Even if there was a problem with the delivery, or the clock was dropped and broken there is the problem with the ease of replacement. If the main stair clock was unavailable, was there NO OTHER clock on board that would have fit? The aft stair case perhaps? Better that stair should have the blank, than the main staircase.
[Moderator's note: This message and the two above it, originally a separate thread in a different topic, have been moved to this pre-existing thread addressing the same subject. MAB]