quad encoder diagnosis

I am trying to use the quad encoders for the first time and one of them is producing errors when I compile and run a program using RobotC. The left encoder functions properly in the debug window, but the right one only fluctuates between -1, 1, and 2 when I move its respective wheels. Do the I2C ports I choose make a difference? I have the terminals plugged into consecutive digital ports (1&2, 3&4). The only thing I can deduce is that the encoder is broken? Can you tell me how to test for certain that it is serviceable or not? Please see the attached screen shots to see the code.
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I swapped the encoder out with one of my students and everything works fine so the encoder is definitely broken. It is brand new out of the box. I see there is a removable cover, can I disassemble the unit and repair it, and if so do you provide instructions?

Hello roccojp,

I apologize about the faulty VEX Encoder, please contact support@vex.com and request a return form.

Also please make sure to include your VEX order number, as its necessary to verify your warranty.
Regards.

-Eli