I let my pads soak in HOT water with APC in a bucket.
Repeat above method one more time. When water is warm enough to work the pads with your hands in the bucket , massage all residues out.
Rinse clean and squeeze dry. If there's built up residue that you cannot work out by hand embedded in...
I just recently started using UWW on windows with a WW glass towel and results are great.
I've also run a strong mix of ONR with a blue speedy prep sponge to get any old contaminants off the glass surface. Streak free shine. The trick to windows is a quality dedicated window towel.
I own a mytee firebird and they are sold here. I've had the same machine for over 2 years and abuse the heck out of the little machine. Best $350 investment for my business. Use it all the time on every detail.
I have not used the vx5000. Just the firebird. From videos I have seen on the vx5000 and using the firebird I can tell you the difference is huge. Vx has more attachments and much higher level of psi to get the job done more effecintly.