Here is a close up of the resistor. I think it's definitely a solder melt. I was also wrong about the value, it's 100 ohm! I've tried a jump wire in it's place and it made no difference, but there was no sound without anything there.
It's in between the volume and the treble controls. The burnt end in the photo goes to the centre lug of the treble (ground?) The bottom goes way off the right of the photo to another resistor approximately (for cross reference) in the middle of the board and between the volume and boost pots (if looking at previous photos or the 'x-ray' photo you will see it).
Originally i also thought it was the speaker, but I've tried connecting different speakers and it's the same. Also following your suggestion, i've just tested the speaker with another amp hooked up and the speaker is fine.
I can't say for certain that the speaker wire didn't touch the speaker, the chassis bottom, etc when it was loose. So it might have shorted something.
This probably has nothing to do with it, but my soldering iron stopped working at the same time as my amp broke!
I'll try and describe the sound in more detail:
The normal input has virtually no clean tone anymore. It's sounds more like the boost input was on full but a really bad version. The decay is splattery and has a bit of tremolo/ocillation breaking up the signal. The boost input sounds like the ghost fuzz has completely taken over and killed the main signal.
Is there anything i can test with my meter?