Hi, Im rebuilding a 6602 amplifier and I am stuck. On the control board, marked 8002831E, there are 2 transistors not on any of the circuit diagrams I can find in the service manuals. They are marked TR15 and TR16. They are close to Switch S2. On the board they are the two close to the left hand switch. The board has been messed with and I want to check what type of transistor they should be. If anyone has the correct diagram I have tried extensively but failed to find any circuit diagram showing these. Any help gratefully received