LOL, you got me doing more research now on this. :)
I'm wondering if this Electrochromic material might be reversible. Because going from the description in my Seiko tech manual for this watch the material gains and loses electrons when electrical potentials are applied to it. So, if a single current could be generated on the diodes over a period of time, they might bake off the accumulated stuff and allow the material to change like it was supposed to. Maybe.. Hopefully.. lol
I found a nice 1993 video on these Electrochromics to help explain what's going on and to give us some ideas.
http://wwwf.imperial.ac.uk/imedia/content/view/559/electrochromic-displays/This might be a task, but I'm thinking of just photocopying my Seiko F623 Tech manual and uploading it, it might be useful if we were to make an attempt to rejuvinate the display. The manual says that applying more than 1.5v will destroy the display on this watch by the way.
This could definately get interesting! I'm at the point where I know at least other members here have an example of the watch, in case mine is destroyed in the process, so maybe we should have a skilled member have the chance to make an attempt to get the display working correctly again. I don't really have much to lose at this point, and I'd feel better if we at least gave this a try, rather than having a dead watch with no hope of revival.
I just wish I could get in touch with Sharp, since they made the display for Seiko, it would be nice to chat with someone experienced with Electrochromics to see if this faded display is reversable.