#1
I got a hold of this amp, but it doesn't work correctly. When I plug it in, the light turns on, so it's getting power. When I plug in any guitar with any chord, it's completely silent. I looked at the inside, and it looks like it's missing a piece called IC4. This is a Marshall G15RCD. The whole thing looks as though it's been serviced in the past. If anyone could help me, I'd very much appreciate it!
#2
Maybe someone scavenged some parts and tossed it.

IC4 is the power amplifier chip, an LM1875. They're pretty cheap. Here's one for about 3 bucks:
http://www.digikey.com/product-detail/en/LM1875T%2FNOPB/LM1875T%2FNOPB-ND/1669