Turn up the volume and the stations are very faint. Bench testing the radio looking for bad solder. Sometimes the volume would come up than go back down finally quit all together. Current draw when running about 2.5 amps. Now when power on the light comes on but no thump in the speaker. I found R64 the .68 ohm fuse resistor is open. Time to replace the power output transistor, if so where do I find a DS-501