Hello,

I personally left my wooden spacebar'd typers as is so that I can imagine the number of people who may have used it and the history that it has lived through. Who knows what may have been typed and who by.
It always seems a shame to me to lose the possible history connected to an object that was probably so personal to someone.
Only my personal feelings, so do what feels right for you.

Alan.

I owned a Remington 17 that was incredibly grimy but worked well.  I used it for several weeks with the grime because I liked the evidence of endurance under adversity -- but finally I cleaned it off because, grime is grime.  But I would never paint over the wear spot in a wooden space bar, or the bare metal one on a Smith Corona Skyriter for that matter; it falls right under my thumb though another thumb made it.