About a year ago, I got my SX fretless, and it came with flat-wounds, which I didn't like. I recently switched over to some new round-wounds, which feel much better :D. I've also been trying to lower the action a bit so I can don't have to push down that far (also to try and get a bit more "mwah"). This is the problem. At the moment, my action is different between each string. The G string is about where I want it (maybe 2 mm above the board), and the lower strings are each progressively higher, with the E string being about 4 or 5 mm above the board (I measure right at the end). If I go any lower on the strings, I've a really annoying dead spot between frets 6 and 8. I'm pretty sure the reason why is this: it's a lined fretless, and around many of the fret lines, the line or the finish (can't tell which) is slightly raised, and causes the dead spots. My 8 fret is definitely the worst offender, but I was just wondering how hard it would be to sand down these dead spots.

What grit sandpaper should I use to do it? And also, is it more trouble than it's worth (i.e. will the round strings do this of their own accord for me)? If I did it, I'd probably have to patch up the finish on the neck, which would probably take time.

Use some 400 grit wet/dry emery paper with some lemon oil on it. then buff with 0000 steel wool .

The use of the phrase "dead spot" here might cause some confusion. "Dead spot" typically refers to a note that is quieter than other notes on the fingerboard because of resonance issues. Spots on the fingerboard that are choked due to high frets or high spots on a fretless are probably better referred to as just "high spots".

At any rate, depending on how high the spots are I would probably start with a little more aggressive cut. Like 320. Be sure to back it with something dead flat so you do only knock down the high spots and do not introduce any new irregularities. Check regularly with a straight edge to see how you are doing.

Yeah, I guess it is just a high spot.

Anyways, thanks for the tips. I'll probably try to remedy it one of these weekends. Just one more question, will I probably have to touch up the finish on the board?

Depends on how it is currently finished. Unless there is nothing on it now, then yes. If there is a wet (oil) finish (probably) then lemon oil, boiled linseed oil, or Howard's Feed N Wax will work. If there is some fancier topcoat (probably not) then you will want to strip what's there completely unless you know what it is, know that a new coat will burn in seamlessly, and have the facilities to apply it.

Even if there is no finish, chances are good that the wood has photodegraded (darkened) and leveling will expose fresh wood. If this is the case, once you've removed the high spots you will want to take the whole surface back to bare wood before oiling/waxing.

Yeah, there's some sort of high-gloss yellow-tint finish on the neck, and I imagine it will be a major pain to strip and redo that.

I guess I can just live with it until I buy a higher-quality instrument.