mark 2c circuit board question

[Tabster]

OK, after looking at a few pics of mk2c guts, I see some of them have a small board glued on a foam cushion on the side and some do not...Mine has a 1/4 jack attached to the red wire on the board...Any help here? Thanks!! ps, mine has the + mod, if it matters

 

[Boogiebabies]

It's the graphic EQ amplifier board.

 

[Tabster]

ok, so what is the 1/4 jack..is it a footswitch jack? Thanks again

 

[Boogiebabies]

There should be two 1/4 inch jacks. Looking from the back of the amp. the left jack is a preamp in/ power amp out jack and the right is either a dual EQ/Reverb switch or EQ or Reverb depending on your amps options.