I've been using Nuti Bullets for over almost 3 years now and the biggest issue I had was the rubber gasket popped out pretty much every usage, I purchased another blade and they both did it. But like I said it was not an issue.
I purchased the 900 and it has been nothing but trouble. I started getting overflow within the first week (the liquid oozing out of the bottom) so I tried using less of everything, which ended up being LESS stuff than I used my smaller original Nutribullet, which is annoying because I purchased the new one for the bigger cup and stronger motor. The gasket never falls out though, whoopee! The past week its been an everyday occurrence, and I'm using less ingredients then I normally use because it started leaving chunks of stuff so I figured it was too much in the cup. So I now have a motor so strong its blowing the bottom of the cup off, because when I take it the off the blades are alway loose, no matter how tightly I screw it on to begin with. I use this every single day and was always very happy with my Nutribullet. Now its just annoying, and I wish I never went to the 900 and I have stopped recommending other people try it because it now aggravates me daily to use it.