I've had a Super Agata for years, pressed thousands of caps, never had a problem. Perhaps the Super Agata capper has undergone some cost-reduction changes, because I couldn't make sense of some of the problems related in the Amazon reviews.
But some problems are clearly operator error: the guys complaining about the mangled rectangular plastic piece had to be using it as a carriage stop while bottling. That piece is used to hold the carriage in its "parked" position for shipping. It can be used for the same purpose during storage, but during actual use that piece is non-functional. The height adjustment is maintained by the lever-actuated mechanism internal to the carriage. As long as you don't release the height adjustment mechanism (by fully raising the lever) it will stay at the selected height from bottle to bottle.
Other than the problems I can't decipher, I suspect the absence of instructions might be at the core of some of these complaints...
Cheers!