If you open it up you should see an aluminum heat sink (a large piece
of aluminum with fins for cooling) attached to it should be a
transistor with multiple legs. It is actually an IC chip. It is the
Amplifier for both the right channel and left channel. It is probly
bad. They are cheap About $20.00 for most. look at the # on it and
order one before removing the old one. Once you have a new one you can
cut the old one out and clean all the holes in the board one at a time.
then slip the new one in place and bolt it to the heat sink first
before soldering the connections. This way the soldering iron won't
overheat the new piece. The heat sink will help keep it cool!! Good
luck!