Re: N5 rock door
If it had been converted to what a '86 or newer machine has for a latch there would be rollers that fit into detent when latched. Older machines had rounded pins that go into detent. There should be a good click when latching the door. Also many machines had been converted to what the '86 and newer machines used. That is a stationary crossmember for trap door to latch onto. Older machines latched onto a plate at front of concave and trap door would pivot with the concave when changing clearance. Newer '86 and newer system was a great improvement. Newer system was available as a kit and maybe still is. The kit included new concave, stationary cross member, and trap door.