I feel your pain regarding the mojo. Ours has been hit and miss for some time now, and for the last few months simply doesn’t work. Even with a different mojo we get the same result, and we are no where near MC 3.5 yet. (MC 2.8.1) And the general response I get from reseller tech support is to ship the whole system, wipe the hard drive and be willing to pay for however many hours it might take to fix it. And since I believe it’s an inherent combination of software and hardware issues, I don’t have much faith it can be diagnosed, therefore, spending lots of money and still having the same problem is the most likely result. Anyway, sorry about the little rant there. Maybe this can help.
The only thing you didn’t mention on your list was trying a different FW cable. And use a higher quality wire as well. FW cables are such fragile things.
Do you have access to another mojo you can try?
Good luck..
John Watts