I think what confuses most is the = and - readings.
You have to remember for example, + .007 and -.007 Mathematically total a difference of .014"
Example: If you zero your indicator at the -.007
Then run the motor around again you will find that the +.007 has now become +.014

if you zero at the +.007, run the motor around you'll find that the -.007 is now -.014

So a .007 offset dowel properly located will get you half way to zero with + / - .0035

A .014 dowel properly located should get you to zero but may impact your top and bottom readings.

So you have to rob Peter to pay Paul and hope Judas isn't hanging out around the corner LOL