Advice On The Mint Tractor

Follow the included instructions.
I find a 16x loop necessary to see the tip of the stylus contact point. The stylus must sit exactly in the target cross for any measurement.
Patience.
Persistence - "good enough" is not good enough.
When the cantilever is aligned it will be equidistant from the parallel lines, viewed from the front. When not aligned properly it will be closer to one line than the other but will not appear to be at an angle to either line.
Once a cart is dead-on aligned you can use it to set up the Mint Tractor for the next cart install.

100x power loop unless you have very good eyes. If you can do it outside or in a screened porch the lighting will help. It's a good Tractor, but it is very hard to see with only 3 to 10 x power loops. Just be patient and you will be rewarded. Good luck.

Patience and great lighting. Both of those and you will be rewarded with great sound.