Verified answer

I doubt the sensors would have anything to do with only printing half a label. I'm not familiar with the E-class series of printers, but the common causes of that problem that I've seen before with the larger M & I class printers can be:

1) A piece of label or ribbon is stuck on the printhead.

2) The printhead is not seating properly on one side, causing the printhead to be too far away from the label & platen roller to apply enough pressure in order to print.

3) A printhead cable is not seated fully somewhere and not supplying the signals properly to that half.

4) The main logic board is bad.

5) The printhead is bad.

6) There is a software problem or label configuration setting that needs to be corrected that controls the print width.

Best of luck.