I just got my big muff through the post, and I'm having trouble working out how to fit the battery.
I've had a look on the instructions but there not any good.

So how do you put the battery in on it?
Thanks in advanced
If there are 4 screws on the bottom, undo them and there'll be a clip for a 9v battery inside.

Wow, you're the second person I've seen to sig me
unscrew the battery cover and clip it in, I used to have one and if I remember correctly then it's like a little silver clip? Just push it in and if it don't work then it might be upside down or something.
Main Gear:

ESP Eclipse CTM I
Dean 'Shards' Razorback
Chapman Guitars ML-1
Ibanez AEL40SE Acoustic
Blackstar HT-5 Mini Stack
EHX Metal Muff
EHX Small Clone