11-01-11: Halcro
P2S distance with the Phantom II can be measured accurately with the cap removed and the Feikert pin lowered into the damping well.
This is recommended by both Bob Graham and Feikert.
That sounds messy. Unless starting with a dry well, the Feickert's pin will be dipping in the damping fluid - which is so sticky a fair bit of fluid will be removed.
You could fashion yourself a perspex location device for the feickert similar to the one used by the Uni-tractor. It uses concentric circles on the perspex plate to locate the tool over the centre point of the bearing. Maybe you could get one of those locating plates from 'dertonarm' - it looks like it might fit the feickert(?).
I personally use the MintLp arc protractor and think its a far easier and possibly more accurate solution.