Hey Salty!
I've been poking at the contraption and only managed to break it in the way you mentioned once. I think something may have happened to the 'on click pos do' event handler inside the contraption? This is the final event handler in the contraption's script, as it (probably) should be:
on click pos do v:get_options[] w:(.7*c.size[0])/count v set_value[v[floor(first pos)/w]] end
If this event handler isn't there to do something with clicks, then clicking the tabs doesn't do anything.
So that would be the first thing I'd check. 🤔 But also, since your actual writing is safe in their own fields you could also remove the contraption and bring in a fresh copy. (Or take a working copy and give it a higher version number so it automatically replaces the old ones when you paste it in...? I think that's how that works. Save your deck first for safety!)