I noticed I had this huge problem getting my rotozip tool
circle cutter to make a cutout the same size... ever.

The centering pin might be loosening up as I work the device.

Other problem is I am using the smallest diameter the
circlemaker has, so I can't simply set it lower.

The centering pin is this big fat sloppy thing. I'd
be better off to use one odf those $6 attachments for
a jig saw, but again, I'm trying to use the smallest
dimension for 4" drivers in an array project.

I don't know if there's any help for this or not (?)

In any case, the box of 50 cent speaks I got on closeout
does not suggest any new tool purchases right now... not
until Sir Fitz gets his line array published. :-)