Thiele cab...help please!

I recently acquired an old Mesa thiele cab (ev speaker, Boogie logo). It seems in fantastic condition for its age...very clean inside and out with original slip case. All electrical connections seem to be fine.

When I first connected it to my mark iv combo (using both the 4 ohm sockets to run the thiele together with the combo speaker) there was no sound at all from the thiele. I tried various speaker leads, different speaker sockets and even a different amp (Marshall jcm800) and still, no sound. After a while it suddenly started working. For the next jam session the thiele cab worked fine, however now there is no sound again.

Does anyone have any ideas why this cab seems to be temperamental?? As far as I can see it is flawless and seemingly built like a tank. Maybe it's something I am doing wrong??

Any help would be appreciated. Cheers!

maybe a problem with the jack plug or the internal wire?

A.

yep. sounds like a loose connection. you'll have to trace it out. could be a worn/corroded input jack, loose wire at the speaker or jack, frayed connector wire... shouldn't be hard to fix, you just have to find the fault.

OK thanks guys!!