So this is not about Ovation but I am hoping that tye BFLG masters can provide some opinion. Last week while I was on Hawaii for vacation I found this (at least 40 years) old 6-string ukulele. It has a lot of mojo, and the Koa fretboard is quite worn and discolored between the frets, with a noticeable "pit" at almost every spot up to about the 6th fret. I think that it plays great and all notes can be fretted cleanly, but cosmetically it looks a bit too rugged for my liking. I assume that there are few approaches ranging from simple clean and polish, to sanding between the frets, to a complete fretboard replacement. At this point I don't really consider the costly replacement option, but am wondering if a sanding and leveling would be reasonable to remove the numerous "pits" or if there is way to also fill those "pits" to keep the dimensions of the fretboard as close to original. 

Nice comments everybody! Hope you don't mind my chiming in d'ovation. Since your Uke is "at least 40 years old" it probably has a flat fretboard? If it does, radiusing the fretboard will take out the pits (at least near the edges), and make the Uke even easier to play. When working on my 1868-5 Rebuild (in its final stages now), the fretboard was in pretty bad shape. It had the usual Ovation standard 10" radius, but Yamaha's 16" radii feel pretty comfortable to me; so the 1868 fretboard radius was compromised and sanded to 12".

Here's a pic before the radiusing. You can see there is a lot of grain lifting on the fretboard (unfortunately, the pits in the 4th fret and lower position are not pictured, but the pits were kind of deep in the shape of the open "D Major" chord.

After sanding with the 12” radiusing block, the fretboard really cleaned up nicely. The larger radius meant the middle area was sanded down with little change in the overall depth of the fretboard at the edges. To my pleasant surprise, the pits were also removed quite nicely.

Here's a Yammy (CPX10) in the rebuild process right now. The fretboard on this one was severly pitted. Even after resurfacing, there was one pit just before the 1st fret that was too deep to sand out. Yammy fret boards are pretty thick so "thickness is not an issue here"; however, if I sanded deep enough to eliminate the pit, the position markers would be at risk!

This one will be filled with a mixture of rosewood dust and CA glue. It will not be invisible, but will be hidden to all but the most suspecting eyes. Whenever I sand any kind of wood, I make sure to keep plenty of sawdust in small sealable baggies. When labeled properly, they really come in handy when something like this happens.

One of the things you'll notice is that the pit stands out if not filled, and looks pretty fugly. With 40 years of use, if your Uke has 4 or 5 of these across the fretboard, it will look pretty funky even if you fill it with a Koa/CA mixture.

Don't know if this is helpful at all, but I guess that's my 2 cents worth! Ooh, class starts in 5 minutes! Yikes! Good luck d'ovation.