You may have seen a few of my posts already. I'm Elliot Marx and have directed the electronic hardware design on the VMS4.
If you have questions about the operation of the VMS4, please feel free to hit me up and I'll do my best to help you address these issues. I'm seeing many of the issues that come up are due to the fact that the VMS4 is a MIDI controller with a built-in mixer. Take your time to learn the product because it's probably a bit different from anything you've used before.
I also have one brief comment. I see lots of quips about the product being Made in China and put together haphazardly. I personally spent months with engineers and production staff in China getting this product working. I know too well about the challenges of making any product in China, but for sure we've put a tremendous effort into making the product sound and feel right. On top of that, American DJ has a very strong QC and support staff ready to resolve issues that come up both from production and from customers.
If you have service issues particular to your product please contact ADJ support directly. These guys are on the forums every day reading your feedback.