The Z2 should be very gentle on paint. The first thing to do if you are unhappy with the Z2's performance is put new AA's into it and run a diagnostics check.
You run that by holding in both buttons and turning it on. Then release both buttons. Once it gets to the purple LED, push any button and let it spin for a few seconds. It will have auto calibrated itself and made sure everything is correct.
It's not unusual at this time of year to hear of people finding that a gun or loader that was working perfectly or that shouldn't break paint suddenly starts doing so. More often than not it's the paint and not the gun or loader.
As the weather gets colder and people are still using summer formula paintballs they are more likely to get breaks in the barrels of the guns or in the loaders.
This has actually gotten even worse over the last few years as the paint manufacturers strive to save costs on making the paint, and the paint is often less consistent and more fragile anyway (especially when using a summer paint in colder conditions).
The first thing to do please is a paint drop test. Usually I like to drop at least 10 and preferably 20 balls at each height. If the first 5 balls all break, I lower down a foot to the next height. Typically I start at around 3 feet. That's the height that quality fragile paint will break around 50/50. Higher and the majority breaks, lower and the majority bounces.
The problem with the cheaper and more inconsistent paint we see nowadays is that 19 balls will bounce at 5 feet and one will break at 12-24 inches. That one will break in your hopper on a dive (or even a reload) and will always blow up in the barrel of most guns.
If you do the paint test and that's all good, then there a few other things to look out for. What batteries are you using? If you are not using 4 AA's please go back to using it with just 4 AA's.
Double check the window in the slide as Ross mentioned earlier. We did see some early units with it forced in backwards. The window should be completely smooth with the slide. There shouldn't be any bump or gap.
Next, where is the paint breaking in the loader? If you have paint all around the inside of the loader that is typically due to
a) Loading a ball that was broken in the pod (shot in the pod, or over/under loading pods so balls break when running).
b) A ball breaking when being poured into the loader (bad paint).
c) A ball breaking on a dive (paint too fragile or a bad ball).
d) Getting shot through the speed feed (this sucks and will need some cleaning.
Typically if there is a lot of paint all around the balls inside the loader and shell then it wasn't caused by the drive system of the loader. Any balls in the drive that are broken are almost always forced down and out into the gun. They don't leave a huge mess in the loader body.
If the paint is breaking but you just see a little paint on the tip of the fins.
1) Loader is spinning too fast, or possibly too hard. Run diagnostics which will slow it down if it was too fast. (If that doesn't work contact paintball solutions and they can take your loader test it, and make sure it is set up better for the fragile paint for you, or talk to the techs at an event.)
2) The loader ran empty and it's sitting at just the wrong height on your gun so that the last ball in the feedneck is getting smacked by the paddles as they rotate. This is an easy fix by just lifting the loader up 1/8 of an inch in the feedneck. This is most likely to solve the problem being noticed here. If you run empty and you hear the loader spinning and hitting a ball with the paddles a quick fix is to just grab the rip drive wheel and stop the paddles until you pot up. (It should automatically start up again when you pot up.
If the paint is breaking in the breech of the gun.
1) It's the paint being too fragile or a bad ball.
2) It's the gun. (could be the type of gun or maintenance issues like ball detents etc.)
3) The hopper is driving too hard (this is unlikely with the Z2, but due to component tolerance issues it may be possible. Run a diagnostics and if that doesn't fix it a trip to paintball solutions would be the way for it to be verified and set up for you).