Hi folks, I've looked at many threads on the topic of low volume. I have already looked at all the resistors in the small circuit that is for the amplifiers and measured them. They are all ok.Except for the Mosfet (Q27621), I don't know how to measure it and what kind of results have to come out. Can you help me with this?And where would I get this mosfet if it was defective?Are there any other sources of error for the low volume?