Right - the Red is positive, the Black is Negative.
The Emitter is one of the three pins of a transistor. The other two are Base and Collector. There's a diagram on the sheet you have.
The torpedo things are resistors by the way. Quite a good description that!
I'd say, judging by what you've told me that the Output Transistors are shorted. Did happen with Roberts sets. The transistors are probably getting red hot which is what the wax is from.
Now - you need some basic tools and a soldering iron. Also a meter. Get down to Maplin, they'll do all this.
For parts, I don't think Maplin do OC81's. Try Past Times Radio at
http://www.pasttimesradio.co.uk/index.html.
Don't put transistors in the wrong way round. And check your wiring before you switch on.
Good luck.
Cheers,
Steve P.