Hello, hello.
The problem you mention looks standard on this model. Usually, due to mechanical damage: center section bent, falling or simply, due to the loss of conductive properties of lead-free alloys, after many years of operation, overheating due to overuse, or even removing the motherboard from the case many times (which in the case of the Model 6 seems most likely). Service intervention will be necessary (desoldering, cleaning and re-soldering an element or two). A very basic repair, but still lethal in inexperienced hands.
