[m.palius]

My MBox 3 Pro died after a year or so. Googling found this thread. Yup, when I opened the box I found the cable connecting the upper & lower boards was loose on one side. Thanks for pointing out the fix & also pointing out the different sized screws. If I'm any judge of me, I would have noticed there were 2 sized screws but not where I'd have to put them during reassembly.

I removed all the screws & nuts. The whole thing more or less falls apart when one does this. I found this approach much easier than trying to stick my fingers into the guts from the the side when attempting to reseat the cable. My experience was the easiest way to reassemble the box is first to screw together the xlr/.25" combi sockets since they're the trickiest, then the other screws and the nuts last.

Best luck everyone with your own repairs,

/mp