not sure about the tubed. i never messed with mine, all i know is i need new ones. the preamp tubes, and 2 power tubes are original in mine and one burnt out, but if there is an old radio shop around you they normally have tube testors. not many guitar stores do anymore, unless they are good ones. and yes that big muff pie is the pedal, nice work +T. haha good luck, also consider cleaning your potentiometers on the amp, and while your at it, on your guitar. i've had some get dirty on my PA, when i moved them, they wouldn't do anything, and werent working unless i really messed with them, but clean them that might help, and its good for them anyway. good luck peace.
matt