Shimano Symetre RI drag stack access??

[gt2003]

I'm servicing this for a buddy of mine.  How in Gods green earth is the drag stack accessed?  There is no screw in the bottom drag knob to unscrew to get to the drag.  Just 2 indentations right next to each other.  I've tried just unscrewing but have
Teisted pretty firmly with no success.  It really can't be that hard, can it?  Someone please help me out here.  Pics attached.

[philaroman]

https://roulementcasting.com/wp-content/uploads/schematic/Schematic_Shimano_05Symetre_1500RI.pdf
NOTE: Drag Knob Retainer RD-8796
there is no equivalent part on older models w/ bottom screw, (which I actually know)
guessing that's hidden while drag is in functional range, but becomes accessible if you loosen completely
that type goes flying...  work inside clear bag to remove

P.S. guessing, the two bottom holes are posts, on the inside, for clicker peg/spring RD-8787/88

[gt2003]

Thanks Phil.  Unfortunately no luck.  Someone on alantani mentioned maybe a c-slot tool that is needed to access the drag.  Oh well, drags are working well now so they just won't get serviced unless someone has a trick.  Thanks folks!!