Appreciate the reply. You're right, KONE Spares still shows several SL boards.
The wrinkle: the SL is 30 years old, KONE marked it obsolete 16 years ago (8/13/10), and it's going dark piecemeal. The car card is already flagged "OBSOLETE – NO LONGER AVAILABLE," and the rest is sell-till-gone. "Available today" and "available when needed" are different things on this vintage. These are for a non-profit, so paying KONE spares prices for shelf stock isn’t realistic.
The way I see it, most SLs are already modernized, and every mod creates a suite of rebuildable boards with nowhere to go - pulls off the machine plus NOS spares bought and never touched. That's the supply that keeps the last few units running after the parts counter empties. Every mod also shrinks the number of machines that will ever need these boards which means this stock is worth something today, less as more SLs disappear. Rather than let it drift to the scrap bin, I'm buying: pulls or NOS. If I gather enough, I don't mind being the guy to call when KONE's bins finally empty.