A web search should find a number of folks who do Yaesu repairs, some who specialize in that product line. Maybe half of them will gladly discuss repair & refurb options, the other half will be miffed at being interrupted from whatever. Not to say that the grumpy ones don't do good work.
I owned a 757GX once, and I believe it's still in service in someone else's setup. However, there may be a number of refurb needs that are expensive, which leads me to echo what others have said: A new entry-level transceiver, or a gently-used one of near-current production might get you more bang for the buck. Trust me, the 757GX was a fine radio 30 years ago but I wouldn't have one as my first & only HF transceiver today. Maybe 2nd or 3rd.