1680 crystal replacment help

[SubKing]

hey all,

so i recently won an original rolex crystal for a vintage 1977 sub of mine off the bay that is new old stock..

i want to do the work myself, i just wanted to know if anyone had a link for me to see just what the best way is to change a vintage rolex crystal and remove it. or if not maybe some of the pros around here could give me a little insight? i have a watch bench with most of the proper tools. i have popped the bezel off my sub many times, i even have a press with all size heads to press the presure ring back on after the new crystal is installed.. i am just a little iffy as this is a vintage. under the bezel there seems to be a metal ring that is around the crystal that meets the case that seems to be on very tight.. i know i must get this off inorder for the crystal to come off... but any advise would be great as i do not want to take this to my local watch maker... i am too picky as they do not do perfect work and i only trust myself inorder to be happy with the work. any info would be very kind. thanks all