DUH I'm embarrassed
I thought that the foot pedal released some sort of latch/spring mechanism. All it does is lift the front of the box up a little to get over the catch. To fix my problem I simply had to lift the box up and pull out. The loose screw had fallen out of where the foot pedal attaches to the box. Screw it back in and all is well. Feel a little stupid for not figuring this out earlier, but I wasn't looking forward to tangling with the compactor and put off checking it out for a few days.