it Only affects to plotters prior to 2012.
I had to change the scan motor because it was giving me troubles.
I ordered the motor to official distributor, and installed by myself. Once time installed it started to work strange, with a lot of errors like "location out of the range", unfinished limit initializations (Head runs to the left limit, but when comes back stops always in the same point.). All of that errors are because roland replaced the scan motor with a new one in 2012. The major differences are that the gear is almost 4 mm small, so now, for each one turn of the motor, the head will run a lower distance.
To fix this you must have the latest firmware (at least 4.50) and then enter in service mode. Go to service menu>system switch> page 16> and change the 5th bit from right to 1.
Also check that the new motor comes with the support plate, because when the gear changed, this did also.