First off, like all detailing issues, we need to start off on the right foot with the proper diagnosis. Most importantly here is to realize the title is wrong. You are using a rotary buffer but asking for PC Help. Based on what you've posted over on my site
The question I have for you is---do you realize that your rotary is NOT a PC and therefore the polishing techniques, speed, pressure, chemical choice, pad choice, etc.. that we discuss here won't apply??
The hopping is common on the rotary buffer when you don't have enough chemical on the pad, but even with a saturated pad, you can still have pad hop. Another problem is that you're using chemicals and pads that are unfamiliar to nearly everyone here on NAM, so you're not going to find much help.
The fact you're using a cheap rotary could also be a part of the problem. I had the Harbor Freight, aka Vector, polisher before I got my Makita and it was a total waste of $60. There is no comparison between the power and control over the two.
If you're seeing color on your pad, there are a few possibilities.
1.) You're working on a paint with a tinted clearcoat (common on Lexus but not BMW's)
2.) You're working on a car that's been repainted partially with single stage paint that doesn't have a clear coat on those parts (this is a new car I believe so I doubt this)
3.) You have gotten the polisher close or over some rubber seals and picked up contamination on the pad.
4.) You polished over an area that had been touched up and you're picking up that paint.
5.) Worst case scenario, you've managed to polish through the clear and into the base. (not likely though possible)
So to address your concerns, you really either need to find an expert--maybe call my friend and forum member Perfection who has offered free help to you--who is familiar with that system--or stop playing with the rotary and get some training on using this professional tool!!!
Richard
