That driver looseness can be causing the flicker. It looks like that driver was made using a slightly thinner pcb and now the ring is not squishing it. You can add a thin layer of solder around the edge to add thickness or maybe make a shim about the size of a grain of rice from a soda can. Loosen the retaining ring, slide the shim under and tighten down. If the driver feels snug then you’re done. If it’s still moving around you may need to make a thicker shim by using a larger piece of aluminum from a can and doubling it over for double the thickness.
You can pop the reflector out, no problem. Just cover the lens with your hand and tilt it over and let it fall into your palm. Don’t touch the shiny side. The oil from your finger will be super visible. If you try to wipe it, it will smear and make it worse. So hold it on the outside.
For dust, you can blow it out, just don’t get any spit on it. Do a couple of practice blows to the side to get any moisture drops out of the way, then blow into the reflector. Or leave it as is. Dust doesn’t hurt anything, it just messes with you mentally if you have OCD. Lol.
The factory will try to use an existing centering ring if possible to reduce costs. Some will have a custom ring made for their particular model. Either way, a tiny difference in thickness can have a noticeable effect. The factory can not take the time to sand or shim each light by hand to get it perfect. So it’s usually “close enough”. Some lights might roll off the assembly line perfectly spaced, while others might be a tiny bit too high or low. Just like with any product.
This is all part of being a flashlight tweaker. Even when the beam looks perfect you might find that shimming the reflector up or sanding it down can further tighten up the beam.
In your case, I would definitely pop the reflector out just to make sure there’s nothing out of place around the centering ring. It’s possible the reflector might be pushing on one of the wires underneath it, or there might be a little piece of debris under the centering ring. You might also have a bit of flux residue that has gotten underneath the centering ring lifting up one side of it. You’re not going to know unless you take a look. I typically will pop out the reflector, lens and bezel all as one assembly to minimize the amount of dust that gets on the reflector.
To reassemble, you can hold the flashlight upside down and drop it onto that complete reflector/bezel assembly. Then flip it over and make sure that you see the centering ring drop down around the LED and it all looks good before you tighten the bezel backup. It should be a piece of cake.
PS, the lower two videos look private. They don’t show up.