Carriage Encoder with Bliss

[Bertwood 1]

I have a 2010 Millie, with Bliss and Quilt Path.  When I pull my machine towards me, it sews fabulous....when I push it away from me it sew irregular, and on the back I have railroad tracks.  Then I go from side to side, I get railroad tracks and irregular stitches.     So..... Am I correct in saying that the Carriage Encoder on my machine is located in the back of my carriage, up underneath it....and I am unable to adjust it as it is taken care of by the bliss system set-up?   Also, the only encoder that I am able to adjust is my Head Encoder?  So if I have adjusted my Head Encoder and I am still getting terrible stitches when I push Millie away from me, or push Millie from side to side.....I either need to retime my machine, or get a new rubber encoder wheel for my Head Encoder?  What else would I do????????    Thank you....anyone??????