Superb! Thank you, Willie! That's more to my taste...clean and lubricate and put it back in service rather than go the new parts route if at all avoidable. You saved me having to figure it out on my own (and likely break one as part of the learning curve).
And of course I realize it's a gas valve, hence all the dire warnings elsewhere on the net about replacing rather than servicing, but if it passes a leak test after careful reassembly I feel confident it will be safe.
Much appreciated and thanks to everyone else who contributed.