Thanks for this. Very helpful. The Feickert has three alignment possibilities, Baerwald (B), Lofgren (L) or Stevenson (S). The only problem for me in this case is that it won't work with a Decca cartridge because that cartridge doesn't have a cantilever and the lines on the Feickert are too narrow to see under the wide cartridge body. So it goes back.
SME Setup With Slotted Headshell
I have an SME M2-12R but I've switched to a Fidelity Research FR-S/3 headshell for added mass. I have a Feickert protractor on the way. Do I just set up like a regular tonearm since I've done away with the fixed headshell? Set the pivot to spindle and then adjust the cartridge in the headshell to the protractor?