First off let me say Welcome to Lets Talk Guild Superdave! Here are a few things to check for on that model to make sure the guitar is in great playing shape. The biggest issue with any Full Hollowbody is Neck Angle in Relation to Bridge Height. I always make sure the action is low and playable at the 12th fret. When you Check the action, Make sure it is to your liking and the Guitar Intonates properly with no buzzing. If the string height and intonation check out the next order of business is to Verify that the bridge Height has Further Downward Adjustment left in it. If the bridge is bottomed out and The action High then there may be a Neck reset in order and those can get rather expensive.
Another thing to check is the frets. Run your finger down the edge of the Fretboard and check to see if the frets feel Sharp. Sharp frets on the edge can be a sign of improper Humdification and shrinkage of the Fretboard wood. This can be fixed by properly humidifying the guitar and having the frets redressed.
I also have seen a few of these Guitars that had the finish peeling on the binding of the Neck itself. This doesn't present a Major issue but if you find the binding to be exposed in any spot you may want t have it sealed to prevent and moisture from getting into the joint bewtween the Binding and Neck wood itself.
Check the string nut on both sides to make sure there are no Cracks in the finish. Cracks in the finish by the string nut can be anything form just finish cracks to the beginning of major problems such as instability between the fretboard and neck itself due to a Deflection hit to the headstock.
Last I would make sure the electronics all work properly and everything feels good and stable, The late 90's Westerly made X150's are some of the Best Built X150's ever to be made and are Highly under rated in my Opinion. Best of luck to you and once again, Welcome!
TX
