Brothers MFC-9325CW Error 28 Drive motor does not start

[abbot7]

I have a Brothers MFC-9325CW with an error 28. I have the left side off and when I power it on the Drum Motor does not start. Any ideas where to go from here? All the drum life are at 44%.

 

[abbot7]

I reset the purge counter to 0000 and I also notice this:
C DEV BIAS = 0V
M DEV BIAS = 0V
Y DEV BIAS = 0V
K DEV BIAS = 0V

1) Where do I go to check these voltages?
2) Which board do these voltage come from?
3) What should these voltages be?