A couple of disappointments here?! first the 3000S was replaced by the 3600 in mid 95!
Worse though and I'm assuming you mean a bit more than just the knob that you turn.
Both model fires, if manual ignition, use the same gas control rod with a piezo igniter set in the rod, this is now as rare as hens teeth and very difficult to find.
On the up side, a broken one is easy to repair and if it's auto ignition? then I have these control rods