On Wednesday, March 4, 2015 at 7:23:03 PM UTC-5, JJ Sinclair wrote:
The root rib bearing spinning during assembly is something all Grobs have in common. With the ship assembled, I would check for any vertical movement at wing tip (with the other wing tip on a stand). Pick up wing tip with about 25 pound force and check for slop. You can feel any movement. If the wings are tight, I wouldn't change the bearings. You could consider gooping up the bearing to keep it in proper alignment for next assembly, something that would keep the bearing from spinning and still allow slight movement. The heavy wax used in a toilet ring might do the job.
Hope this helps,
JJ

Reread the 1st post, they have an issue of NOT being able to align the "ball" easily.
;-)

Movses....... I would try using a bar (maybe brass or aluminum) inside the "ball" and working it around while spraying some WD-40, PB Blaster, Kroil, etc. on the "ball - socket joint". You will likely wash out some rust and maybe smooth some rough spots.
I would just do enough to get it "free" as you don't want it to go too loose, then you're into what JJ was referring to.
Wipe everything down to get it clean & dry once the ball is free.
Keep a bit of a light oil on the OD of the ball once it's free.

PS, I would use plastic sheeting or similar to keep whatever spray you use from soaking into the rest of the wing root.