Lovely example from the 600 series.
Only two things wrong with it.
It's a date model (I like the no-date)
and
It's not mine 😁
Basic instructions for your watchmaker.
Carefully disassemble.
Clean case and caseback in ultrasonic after removing crystal.
Clean, inspect, assemble/lubricate/regulate/adjust movement.
Fit new crystal if the original can't be polished or if it displays sub-surface crazing.
Pretty basic requirements.
It's important that you try to keep as much originality as possible so no buffing/polishing unless the watchmaker is highly skilled at this art.