Originally Posted by bikingshearer

Be sure to ask about/check out the bottom bracket threads. In the early 70s, Jackson had problems with mangling an unfortunate number of their BB shell threads such that bottom brackets would not stay put. I had one that resulted in my getting an exploded view of my bottom bracket assembly in the middle of a ride (and in the middle of the road)

I was a teenager at the time and had no clue how to deal with it. A good, reputable shop solved the problem with a Phil Wood BB and red Loctite. That kept the problem from ever rearing its ugly head again, so a work-around is possible and bad threads don't have to be a deal breaker. Using red Loctite, however, is a pretty permanent solution - don't do it unless the BB can stay put without servicing for the rest of the bike's life.

Odds are it isn't an issue with this particular frame; as with Mexico-built Benottos that had overcooked tube joints, its likely that all the problem child Jacksons were discarded long ago. But it would not hurt to do some due diligence so you know what to expect.