Roamer Stingray Chrono Val 23

Couldn’t help myself and added yet another slightly gauche 70’s Chrono to my collection.
Can anyone help me with getting access to the dial of this watch. Once you have freed the mechanism from the bracelet and housing, how would you recommend I lift the crystal ? I believe these to be front loaders, no removable back with split stems ?
I also need to replace the o-ring on this, similar to the one used on my Speedmaster 125 however this is much much thicker it would appear. Anyone have the details for this o-ring ?
Thank you

These Roamer Stingrays with the Valjoux 23 are such sleepers. Amazing movement, wild dial, and that bezel is peak 70s.