output doesn't seem to work. i can get a very faint, distorted signal out of the left and the right seems to work fine. the master's left side lighted volume meter isn't showing anything. just the right. left and right are working out of the headphone jack. Checked continuity of ic556 &ic557 also input and output voltages of voltage regulators 7808 7815 7908 7915 all reading ok, where should I start looking to rectify thanks in advance