VIntage 1968 Marx Fort Apache Tin Litho Carry-All Play Set #4685 with Accessories

Has rust and has hard brown crud inside case on terrain and building. I could not figure out how to open the case all the way so I'm not sure if that needs repairing or if I'm just clueless on how to open it completely. One of the small walls of the case is off.

Case has lots of scratches on outside and wear. Missing handle, but it latches.