hmwoodfm, I guess the only way to know if something broke is to have a look. Lift up the mattress and remove the luan floor in that compartment. Should be about four screws. You will be able to see the mechanism and determine if something, or what, is broke.
If you heard a pop, and now it don't work right, there is a good chance something is broke or came loose.
Let us know what you find out when you get in there.
Peace
Dave