James Coxon

I own a Gretsch Streamliner G2420 and I've got this problem with it where sometimes I get no output from the guitar. I put my guitar lead in the output jack and get no sound through the amp sometimes. I have to wiggle it around to get an output but it can go off after a bit of playing it, almost like it looses the output. I'm not sure what the problem is exactly, wondering if anyone had any idea whether it's the output jack or electronics or what. Also if you have any idea how much a repair job on it would be that'd be great (from a repair shop, don't trust my self), just looking at selling it. Any questions feel free to ask and cheers.