So i just picked up a vintage Casio from a friend and was just curious as to the value. I gave him 50 bucks because i fell in love with it and liked that it was different and vintage. I know they were made starting in 1978. I have found a lot of interest in them from doing google searches. Also if anyone if familiar with them do you know how to fix the sticky buttons? They tend to stick when you push them. I have taken it apart and cleaned the small amount of scum around the edges of the buttons. I noticed each button has a very small o-ring to seal the watch from water, so i am thinking maybe the o-rings are old and stiff. Let me know if anyone has experience with this.