I recently got a brown Vibrolux. When I pulled out the chassis, there were two pairs of diodes bridging pins 4 and 8 and pins 6 and 8. Why would somebody do this and is it OK to remove them? The rest of the circuit, with the exception of replaced electrolytics and a couple of resistors looks original and matches the schematic. The amp also takes longer than usual to shut off after the I flip the power switch...maybe 15-20 seconds of decreasing volume. Any ideas why this might be happening?