Quote Originally Posted by mikeb_z5
...inserted my new used 4x5 glass carrier and rechecked alignment. I was surprised to find that alignment had changed about 1/8" on the target somehow.
1/8" variation on the target doesn't sound like a lot. Depends upon how high the enlarger head is set (what would otherwise amount to magnification). Possibly the glass in the carrier is providing its own reflection and may not be completely plane parallel. The question is whether or not the negative itself is orthogonal to the optical axis. But again, 1/8" doesn't sound like a lot....

Can you tell a difference between prints made with the two different carriers, but with the same negative and same magnification?