I have 2 of these machines. The first was very reliable with the exception of the green head drying out. (this was an issue with ColorBurst not using green ink). The second has had a mother board and reduction belt replaced. Right before it went out, you could hear a small tear on the belt flapping in the machine. It sounded like a baseball card in a bicycle tire.
When our belt was replaced, I had wait a day for the tech to receive a special sonic micro tensioning tool. My tech replaced the belt along with the gear but not the motor. He then used the special tool to adjust the tension. Was this the case when your last belt was replaced? My belt was replaced in late September for reference.