Hi Martin, welcome to the Forum 8) .
Re. info. before going to check the guitar ?
Serial Numbers - guitar should have a 7-digit serial number impressed into the wood on back of headstock ? the first 2 digits give the year, if it?s a 93 model then number should be 93xxxxx ? see here for full list and explanation of dates & serial numbers http://www.tokairegistry.com/tokai-info/tokai-gibson.html Watch out for inked serial numbers (ie as opposed to impressed) ? inked may be fine, but do a search here & check our numerous discussions on that. If there?s no serial then it suggests the guitar is Korean rather than Japanese (may be OK, but big price difference).
Control Covers ? look at the back of the guitar ? Japanese models have black plastic covers (ie control covers), whereas Korean invariably have white covers. Hans-J referred also to the truss rod cover (on headstock) ? your picture shows typical Japanese 2-screw type, however, note that Korean models mostly have 3-screw truss-covers (truss covers & control covers can be changed of course).
Which Model? ? when new the guitars have a little oval sticker on back of headstock (sticker states model number), but stickers are often missing on a used guitar. Look carefully at the maple top ? plain-grained tops are ?always? solid maple, & should be 2-pieces matched along a central seam ? highly flamed/figured/quilted tops are usually veneer on top of plain maple (except on top end models, which have solid flamed top). Lower models usually have 2-piece or 3-piece back, & conversely higher models usually have 1-piece back, but note it?s often VERY difficult to spot the seams (especially on ?darkback? models), best to look at edge of body near rear strap button. Model number may be stamped in pickup cavities. Also, look at the ?pearl? inlays on Fretboard ? on lower models these are often inaccurately cut with rounded edges & black filler around the edges, whereas on higher models the inlay is usually cut sharper with neat edges & little or no filler. Fretboard itself may show more grain & colour variation on lower models, often more uniform on higher models.
Perhaps more important - need to check how it plays, see if action is OK without buzzing or choking, check truss rod is working OK & sight down neck to check bow/relief ? see if bridge or tail-piece seem excessively high or excessively low ? bend the top 3 strings hard & see if it holds tuning ? check any non-original parts/changes ? does it sound good (if not, then check height of pickups...they're often set way too high, or sometimes too low ... very old strings can also sound awful)? Etc :-? .
Ian.