Lift has become something of an hysteria among Rickenbacker bass owners. The truth is, most of the time it is simply nothing to worry about. As I stated on the other thread, there are two kinds of lift. Real and false. Real lift is an actual deflection of the zinc body of the tailpiece. False lift is when the tailpiece appears to have lift because of the underlying wood is not totally flat. I believe false lift to be far more common. Hand crafted wood items are seldom if ever laser-straight and true. Subtle variations serve to make instruments unique and interesting and in them selves are not a problem. Now consider that the RIC tailpiece is a fairly long flat-bottomed part. Because it is straight and rigid it will tend to highlight slight imperfections in the surface of the wood sometimes giving the illusion of lift. Also sometimes the tailpiece bottoms out in the route slightly and does not seat all the way, this is again variations due to sanding and finishing. I believe this is what most people perceive has lift. None of this is truly problematic.
There is also real lift which does happen but is seldom detrimental to the instrument. I own some Ricks with real lift and they settled in and are stable. In extreme cases though the finish flakes off of the body on either side of the tailpiece right at the point of inflection but that is really not common. My 4003SPC Blackstar has this problem. Someday it will get a new tailpice (as soon as I can find a BT 5 screw) and go to Paul W to have its finish repaired.
Real lift is usually caused by a gap under the bridge part of the tailpice. The well where the 3 screws go is sometimes too deep so the wood and zinc are not touching. If the screws are over tightened in this case they can actually bend the tailpiece upward a bit at the ends enough so the string tension can pull the whole assembly forward causing lift.
The height of the fingerboard relative to the body face can vary. On basses where the height of the fingerboard is greater than average, the bridge has to be adjusted up to get the strings to clear the 20th fret. The higher the bridge the sharper the string angle. More extreme lift seems to happen on basses with sharper string angles from the saddles to the stop. On the plus side, the higher the bridge the easier it is to access the saddle adjusting screws.
High tension strings can further increase the chances of lift.
Nearly all cases of lift are stable and not a threat to the instrument in any way. If it bothers you, have your tailpiece shimmed with wood or use washers to fill in the space. This won't straighten the bend but it will stop it from getting worse. If you don't shim or washer, be careful not to overtighten the three screws under the bridge. Shimming can actually improve the depth and clarity of the low notes by increasing the contact area under the bridge. This was a totally unexpected consequence that made me fall in love with my '80 4001 after suffering years of disappointing low end.
