Vintage Synth Repair

Hey,

I purchased a Farfisa Professional a few weeks back and I'm having 
some volume issues with it.  
I brought it to my band rehearsal the other night and I found that I 
was unable to get enough volume.  We are not a overly noisy band, 
just a guitar, bass, and drums (indie pop-rock a la "the shins" 
or "pavement") but for some reason, it would just not go loud 
enough.  At first I ran in through our PA system, which is what I 
usually do with a crappy Yamaha synth I have from the early 90's, and 
we had it cranked and it was barely audible.  Next, I tried to play 
it through my guitar amp (Fender Twin '65 re-issue) and I had the 
volume on 8 and it still wasn't cutting through the other 
instruments.  There's no way I should have that amp on 8!  When I 
play my guitar through it, I usually have it on 4 and it's absolutely 
blaring.
I looked at the original specs on farfisa.org and I found out that 
the organ originally came with a volume pedal (mine did not).  
Perhaps this is the problem?  Since there is no master volume on the 
organ (just faders for the flutes, percussion etc...) this is the 
only thing I can think of.  So, do I have to find the original pedal 
for the Professional, or is there a volume pedal on the market today 
that will suffice?
Thanks for your time,
Matt