Geoff I must agree with Mike.
I have read so many "tips" on what to do and as with many things the attempts of authors to explain the matter fully sees an un necessary complexity confusing the reader... and when one is cold tired and frustrated trying to align needs to be simple. I intend printing out your words and pasting them on my pier mount
. Make up a brass plate even
Excellent explanation that should remove the fear of the proceedure for the novice.
alex