Its time to replace the strut inserts but I just cannot budge the large nut at the top of the insert tube. Right now, the various links have been undone and the top of the insert removed from the shock tower so its outside the wheelarch. The book says; unscrew with a special holder and screwdriver. I have applied lots of PB blaster, tapped with a hammer, let soak and used two pipe wrenches to unscrew this fitting. No luck. I have had less difficulty undoing steam heating pipes. What am I missing????? Thanks for any suggestions