Akimo, since you revive this thread let me give my opinion on Feirkert and Mint Lp. Feirkert is good to set up spindle to pivot distance. It's accuracy varies depending on whether it's pivot point is obvious like Schroeder tonearm. I have other tonearms which does not show the exact pivot point. Beside this, the pin that hang from the end of feirkert ruler does not allow exact vertical plumbing simply because hole that hold the pin ( by a screw ) is too large to allow exact vertical plumbing. Hence the inaccuracy. Beside that the line and dots are way too large. No way it can be accurate
As for mintlp ( I have all the mintlp for all my tonearm -3), it's definitely much more accurate but back breaking and tiring exercise. The loupe that Yip sold is definitely difficult to use ESP for certain catridges with cantilever within the body eg zyx omega with a ball blocking the vision. For those with such catridges , I strongly suggest to buy a specwell 10 x 20 monocular, with a tripod mount, close up len +2dpt. You will find setting the inner null point and checking the parallax error much easier. Check out optimalowvisiondotcodotuk. It's not cheap but who says this hobby is cheap?
As for mintlp ( I have all the mintlp for all my tonearm -3), it's definitely much more accurate but back breaking and tiring exercise. The loupe that Yip sold is definitely difficult to use ESP for certain catridges with cantilever within the body eg zyx omega with a ball blocking the vision. For those with such catridges , I strongly suggest to buy a specwell 10 x 20 monocular, with a tripod mount, close up len +2dpt. You will find setting the inner null point and checking the parallax error much easier. Check out optimalowvisiondotcodotuk. It's not cheap but who says this hobby is cheap?