I don't think the jack is bad.
The Mesa works fine with the daisy chained Bergantino cabs.
The Warwick works fine with the daisy chained Mesa cabs.
I found this in the Mesa manual:
The amplifier incorporates a pair of SpeakOnTM NL4FC connectors wired in parallel that mate with either NL-2MP or NL4-MP plugs. Cables using NL-2 plugs contain only 1+/1- terminals and will always be correctly wired for use with the amplifier, but cables using NL4 connectors come with different wiring configura- tions. If using cables with NL-4 connectors, they may be constructed with standard 2 wire cable and they must be wired 1+ to 1+ and 1- to 1-. 4 wire cables are fine as well, terminals 2+ and 2- are not used. The cables to avoid are what are called NL4 bridge mode cables, which are typically 2 wire, and wired 1+ to 1+ and 1- to 2+. These SHOULD be clearly marked but sometimes they are not, so be aware of the possibility.
Well seems like something wired weird
happens. good luck!