just a little "psa":
My ZF BB54 stopped working today. No reason I could think of, but the seconds hand just wouldnt work. I expected some damage / broken movement, so I started looking for a movement I could swap in. Still no clue what that movement should be as I would like a no-date/no-ghost-position movement w/o modding the keyless myself.
I opened the watch up: A tiny screw from the movement loosened and fell into the balance wheel, blocking it.
(excuse the bad pics, I had very bad lighting - perfect condition to work on watches, but I wanted to know whats up

)
With the screw removed (and put back in place, but that shouldnt matter

), the watch works again. No clue if this will affect how the movement runs - I will keep an eye on it.
tl;dr: Check the screws of your a2824 ...