Did you also make sure the belt's gear/pulley is tight on the motor shaft? I've had one or two instances where the set screw came a bit loose and caused the affected parameter to drift. Aside from that and what you already tried, this is unfortunately one of the common issues with low-dollar moving lights. Drifting a few inches isn't horrible though - I've seen much worse from generic fixtures, to the point that it can't hit the same location twice! There's a reason why some lights cost $100, some $1000, and some $10,000... Best of luck though!
Thanks! Yes, I've opened the first one and made sure the pan/tilt belts were tight. Had to pull just a bit to take a little slack out. Didn't do a lot to fix the issue, so I've gone through turning it on & off and doing tests with that, with both my DMX software open & closed.
Seems the issue arises when I turn on the unit, it goes through it's first initial panning check, and goes to Zero like normal, before I start any scenes. It's almost like it resets its' own XY parameters so that it goes way too far off target when I start up the first scene (pointing at a mirror ball.)
It's got one of those little spindle catch things around the panning gear that hits a sensor switch to start over when it's reached its' maximum pan rotation. I then tried creating a "calibration" scene, if you will, with some wonky rotation effects. After running that, I reverted back to my first initial scene, and it had at least moved the beam over the mirror ball.
Sooo, anyone have any good ideas for calibration-type scenes?