G series, right? early/brown E-eqs have the filters engaged as soon as you hit the eq button (ever so slightly), but that's not the case with yours.
most likely it's due for a recap, loss of bottom end is one of the symptoms of dry caps. unfortunately that probably means the whole console should be done, not just the eq cards.
do you think this only occured recently? the alignment could be off as well, but they usually don't drift much. definitely re-align after recapping tho.