Thought I leave some inspiration for the 606 owners. This here is my SP that I bought in 2006 brand new when they were going for $700 USD. I hardly used it, I bought it for the sake of just buying another SP brother for the SP fam; because we all had to have them all at one time.
So now fast forward 15 years later, I dusted it off and the knobs crumbled and cracked on me. Also the coloring of the grey parts were a yellowish brown in some areas. Fortunately, it was all cosmetics, the inside was brand spanking new. I replaced the knobs with black metal guitar knobs; be sure to get Alpha and not CTS sized knobs if you wanna good fit, however there are knobs with adjusting screws to tighten them too. I just like knobs without those little screws. Then I painted it black and sealed it in clear acrylic.
Don't think I'm a pro or anything. I did not take it apart to paint the pieces, I just used alot of blue tape and a razor blade.