Removing bottom roller plugs

[Labparamour]

Hello all,
I noticed a leaking roller on my 450B (guess I could take that as a sign it has lube).
Searching the forum I've found recommendations to replace plug w button-head fitting and use cornhead grease.
I also noted one member cleaned the plug by spot blasting and soaking with penetrating oil.
My plugs are in something fierce!
My next step is to get a 5/16 impact hex and rattle it lightly and work up...hoping not to strip.
I'm looking for any other techniques or recommendations for removing the plugs.

Thanks,
DB