Hi, everything worked perfectly last time I used the Star Go system. After a couple of weeks I started the motors and at first I noticed a strange sound coming from the two motors (as if they were rubbing). Days later, one of them is presenting a high-pitched sound, (different from the previous sound) that appears when turning (not always) and the motor stops. When this sound ends the motor continues working as if nothing had happened. I tried another engine and it did the same. What's wrong? Will it be the controller? It is only six years old and has barely been used. I checked the power supply (correct, checked two different ones), running at 15 volts. The problem appears at different system speeds: medium, fast, ultra) and with the motor alone (out of mount). I contacted Avalon Instruments twice, but received no response. Could someone help me? Thank you.