Dev. Home error can be fixed by stretching out a solenoid spring on the
side of the printer. The solenoid acts as a clutch to stop the spinning
developer actuator at the right spot.
The problem is that the spring gets weak over time / the cogs round out
over time and the solenoid finger is overcome by the spinning cogs, and
resulting in selecting the wrong developer.
Open up the right side (power cord side) of the printer (take off top
cover, then take off side cover). Then, find a solenoid (little metal
square) that touches the white plastic vertical spur gear. Take the
spring off the solenoid. Now, put the spring back on - only this time
you will attach one anchor point to the middle of the spring as to
pre-stretch the spring for more tension.
More pictures of the solenoid on Facebook: