or knife into the track or a screw dropping into them.
Find some big healthy people to tilt the table back and forth and see if something moves around inside. If there is, then it’s only a matter of getting the object to go somewhere where you can grab it and pull it out. If you get the table to work again then rubbing a candle on the rails and slides will help lubricate them.
It’s also possible the rails might have loose screws or have split somewhere, but that is less likely. There are a lot of things that can jam the table but usually careful poking and moving things around will reveal the problem so it can be fixed.
Good luck with the repairs.