In case there is anyone out there thinking of defretting their bass, I thought I might share my recent experience. I have 5 basses, one of which is a 20 year old Yamaha BB400 P bass. I couldn't really justify buying another bass, but I really wanted to try fretless. Anyway, not having ever done anything like this before I tried my hand at defretting the Yamaha which I didn't use much. It was really much easier than I thought. I used three references, a book, the internet and an old bassplayer magazine article. I wont go into all the detail here, but I used styrene inserts as line markers which I bought from the local model shop. Superglued them in. Filed them down with a chisel and sanded the entire board with medium and then fine sandpaper. As the board was Rosewood, I coated it with an oil based polyurethane mix. Two coats. I files the nut down a bit so the strings would sit about a bit more than a business card thickness from the board. Finished it off with Thomastik Jass Flats and adjusted the neck and intonation. The finished product sounds great. Emough Mwah but not too much. I want to use it to play jazz and for that it sounds great. If you have an old bass you'd like to defret. Do the research before hand and go for it. It's easier than you think.