Ye Olde Inn

One thing I was never sure on how it was supposed to be played in the original game is the rules around dangerous ceilings in this quest

The rules in the Quest state

The spaces marked with a falling blocks show where the ceiling is dangerous. Any player who moves onto one of these squares must roll a die. If he rolls a 5 or 6, he will lose one Body point from falling masonry. If the player is wearing a helmet, and has the helmet card, then he will only lose a Body point on the roll of a 6. Monsters are not affected by the falling block squares, as they are familiar with the passages. Do not place the falling block tiles onto the gameboard.

I always took this as a special rule, a special exception, intended for this quest only, that the falling block icon on the map was intended to depict this new "dangerous ceiling" feature instead of the usual use of this icon in combination with the arrow icon as used elsewhere in the quest book to indicate a falling block trap.

So, setting aside the minor point that "player" should read "player character" (and pausing only momentarily to note that "has the helmet card" shows that the original version of the game expected players to actually have the equipment card so cards limited equipment) I always assumed the following;

1. This new feature isn't a trap and cannot therefore be found through searching or disarmed/removed (the text doesn't mention the word "trap")
2. It affects every player character that moves onto one of the indicated squares, but does it affect them every time they step onto each of the indicated squares or is each one a one-off event that only affects them the first time them step onto a marked square?

I think is any time a player step into it. At least I always played it that way...

I would think that if you're diligently searching a hall for traps, it'd be really strange to -not- notice the unstable ceiling. At the same time, I would think this hazard cannot be "disarmed" as it lacks any specific triggering mechanism, so it leaves the heroes with the option to either take their chances or avoid that area. Also, while I don't think the triggering of the hazard would depend on who entered the space (ie. no reason it wouldn't hit the same character more than once) I think that I would give it a limited number of occurrences, maybe roll a red die, simply because logic would dictate that there was eventually nothing left to fall, and/or the hallway -would- eventually become blocked from repeated collapses without some kind of limit.

When I've played it, we always took it as a one-time per square. Not detectable because it's not an actual trap. You wouldn't necessarily see a crumbling weak spot in the ceiling before it collapses. The vibration of walking around would be the "trigger".

I'm inclined to agree, the setting of that quest in an abandoned and collapsing temple, implies that the whole thing is unstable and liable to be dropping masonry so being able to spot the danger of this on a specific square seems unlikely to me.

I can accept that according to the rules that it could be either one-off or a repeating hazard, the rules aren't clear enough to determine which, but I prefer to play it as a one-off hazard, mainly because if heroes do step on the square again it is generally through mis-remembering which specific square was the "live" one caused by the square not being indicated by a tile, for me penalising heroes for not introducing extra admin around marking the square themselves or drawing a mini-map or whatever that would be needed to avoid this situation doesn't seem appropriate, if it was supposed to be repeating then a tile should have been introduced, one wasn't so one-off plays better in my opinion.

Playing it as a one-off is basically treating it like drawing a hazard card, except specifically located on the map because you can't search for treasure in halls. I can see that.