Fix Marshall guitar amplifier I and my wife go to Okinawa's pub close to our flat. The meal in Okinawa is delicious and Health. We have been to the pub a lot of times. Therefore we got close to the owner in the pub. One day, He requested to fix his guitar amplifier to me. I agreed his request and connected my guitar to the amp in our flat. The amp sounds loud suddenly. If the knob turns, the amp sounds rasping sound. I tried to clean the contacts of the switch, the potentiometers by using special spray. But the rasping sound didn't leave unfortunately. I ordered new the switch and the potentiometers and replaced their. The rasping sound and suddenly loud sound left. I brought the amp to give him to his pub. I gave him the amp. He smiled and appreciate to me. I was very glad that I have electric circuit skill. My job is not related electric engineer. But I felt that I can contribute to help electric some problems.