:Hey There,

I too had problems with a ( commercial ) Dob/Newt. I picked up a copy of "Star Testing Astronomical Telescopes" and had a lot of my fears put to rest. It goes through on how to collimate the optics of several types of scopes, including Newts. (this alone was worth the price of the book.) More importantly, it shows what different the problems look like in the EP, so you could possibly narrow down the problem just by star testing. IT also goes into some of the math involved with optics, so the more deeply involved ATM'er might find that useful as well.

Good luck to you,

Thad Robosson