Bomar will make the crystal for the element.
It looks like the cover of the element is soldered in place. I did not go any further.
Bomar recently quoted $50 per crystal, 8 weeks delivery for the MT500.
Bomar Crystal | OCXO, TCXO, VCXO, Clock oscillators, SMD crystals and oscillators
Bomar Crystal supplies both thru hole and surface mount OCXO, TCXO, VCXO, Clock oscillators, crystals, resonators, filters and inductors.
www.bomarcrystal.com
Bomar recently quoted $50 per crystal, 8 weeks delivery for the MT500.