There was nothing wrong with the wiring or electronics, that guitar had the crappiest pickups Gretsch ever used. It had what I like to call Ho-humtron AKA Hi-lotron pickups. For some strange reason Gretsch starting using these horible pickups in the late sixties. The Gretsch pickups that scream and give that thick tone a'la Brian Setzer are the Filtertrons. If you are interested in a Gretsch guitar make sure you are buying one with the Filtertrons.
I think the new Gretsch guitars come with a reissue of these and some come with a reissue of the DeArmond pickups found on Grecsh guitars from the late forties thru the late fifties. DeAronds are great pickups to have. I have a late forties Gretsch Eletromatic and I can get blues, jazz, rockabilly, and honky tonk, tones from it------as far as cost, most new gretsch guitars are in the $1000 to $3500 range. for a QUALITY vintage Gretsch expect to pay anywhere from $1000 for a base model hollowbody with one pickup and no bigsby to about $2200 for a double aniversary hollow body to $2500 for a solidboby Silverjet, Sparklejet or Duojet, $3500 for a solidbody Roundup, $5000 for a fifties 6120 before chet atkins had gretsch close the f holes and make the body thinner, to $9000 for a White penquin or a White falcon.
I would stay away from the mid seventies stuff all together.