FLX10 Hardware/Software Problems

I have 2 flx10s, the problems Im about to explain are happening on both.  Running Serato DJ Pro.  

1.  When engaging the Color EFX Pitch button, with the channel knob at zero (12 noon), I get an audio distortion on the master.  If I move the channel knob either way off of zero (12 noon), the sound goes away.  This happens regardless of what channel is currently selected or going to master.

2.  On channel 1, if I have one of the 3 stems buttons pressed off (not lit up) on the effects bank 3 stems buttons, I get audio artifacts on the master.  This does not happen on channel 2, 3 or 4.  This is a HUGE problem.  It makes sense that if any of those 3 stems buttons are pressed off, it should not change the audio on the master, unless I have the blue engage button on.

Also, who was the mastermind to put the booth knob a half inch away from the master?  Super fail.  This is a Me problem, not a You problem.  Think of yourself mixing and you need quick thinking, and you grab the booth knob quickly for more volume and accidently turn the master up.