I worked on a prototype board that was getting a little older (I did not wrap the original), apparently the tension of the wrapping tool was off or something else did not go according to plan during the original build because quite a few of the connections were flakey and had to be redone. This can be pretty tricky if there are sometimes 6 wires running to one pin and the whole thing is a rats nest of identically colored wires.

I did get it all sorted out and working again but that wasn't my idea of having fun. Fortunately I got into software from hardware or I would have likely given up. You know you have a nasty problem when tapping the board can make it crash. Shades of Gollum and Coke.