Benchmade 665, Help!

[Subzerodsk]

Picked up a bench made 665 satin at an estate sale for a good price. Beautiful knife but I hate the assist. I tried to disassemble but got stuck. Does anyone have any knowledge on how to remove the spanner nut or to disassemble a different way?

 

[Keyman]

Initially, I used two tools & pushed on two of the three legs of the nut in the same direction, at the same time & was able to break the nut free. Once broken free, the nut will turn easily.
Once I had the nut removed and in hand, I made a wrench using a scrap piece of G10, 3 small roll pins & a drill.