My Reciever Only Has Output On 1 Channel, Is There A Part I Should Check?

I bought a used one and there is only output on one channel. i replaced a dozen capacitors and i ordered a (78M12A. jrc. M1037W) due to you could see it was getting hot by seeing the discolored solder joint. infact when i unscrewed that transistor ( same small board that has the "1STK4151V:The Stereo amplifier chip) from the heat sink then turned on the receiver it power up then shut down within 2 seconds. When you touched that transistor it was extreemly hot, so i beleive that part was bad. Whether i listen to the speakers or the headphones it doesn't matter, there is only one channel that works. I can hear white noise on the side that doesn't work "faintly" Do you have any idea what may be wrong or where to look? any tips would really be appreaciated. Thanks, Henry (616-322-2439)