Non Trivial. So much copper in the PCB.....
My count, looking at the cut edge with a loupe, was 10 layers. Didn't even faze my Metcal, and it's one of the wimpy SP-200s.
Perhaps you need to get a man's soldering iron (But not so manly as to constitute being South African).
For those of us with Metcal in the future, or locked away hostage against some government's beaurocracy... I found that mine came apart
very easily using the "apply lots of flux & leaded solder, heat, pry a tiny bit, then move onto the next pin" method.
Difference in my case was I added preheating with my hot air gun, and handled the thing with gloves so
I didn't stick to the PCB. Not enough heat to get the OXCO hot... but raising the temp of the PCB just 20-40° makes a huge difference in how easily it all desolders. Even a hair dryer can deliver enough heat to help.
mnem