Thirty five year old stereo receiver finally failed. Output transistor 2sc2525 failed along with 4 amp fuse. Replaced the 2sc2525 transistor with an equivalent transistor. Replaced fuse with a 3 amp one. Turned on the stereo and both the black transistor (2sc2525) and the green one (2sa1075) next to it on the heat sink failed. The fuse did not blow. I will order the original transistors but wonder why the transistors are failing. Thanks.