Hard time identifying crown replacement 980.020 Professional

Hi there,

I've decided to fix up an old Heuer 1000 (980.020) and I'm having a bit of a hard time finding the right type of crown replacement. I wondered if anyone might be able to shine some light on the subject. It seems to be a push-down, but every replacement I can find seems to be screw down. Hmm

I'm also wondering whether the dial has tritium lume (no T-x-T on my dial, but every other 980.020X model does seem to have the tritium lume). It's clearly been re-lumed, but I'm just wondering what's underneath.

Any help much appreciated.