Well, I finially secured a 4005 a few years ago and at first I was sorely dissapointed with the sound...mainly a plink-plunk noise instead of the deep bass tones I was used to in my Gibsons and Fenders.
Certainly part of the problem was the pup placement. A former owner had even added Bill Lawrence pups to try and get a better sound and the guy I bought it from had re-installed some toasters. The action was high but I was able to get the neck nice and straight again and the action is low and smooth now. The main culprit for the weak and sterile sound was the .0047 cap...when I removed that, the sound vastly improved...still, not as ballsy as my Gibsons and Fenders but quite a big improvement over the former capped version.
If it was ever re-issued (not gonna happen) with a better bridge, high gain adjustable pups with better spacing and maybe even higher value pots you might have a pretty nice bass. Do I want to sell mine? NO!! The neck is thin and great and it is one of the coolest bass designs ever and going up in value every year. When I grab a bass for playing around on, just sitting on the couch and working out parts, without having to plug in, it's always the one that I reach for!