Korg Poly800/EX800 Users

I have forgotten to introduce myself to the group..

My name is Aaron and i have been doing electronic music for over 10 
years. My studio now consists of:
 
synths: Roland Jx8p, Yamaha DX7, Korg PolySix, Korg Poly800, Ensoniq 
ESQ-1, Oberheim Matrix 1000, Sequencial Prophet 600.

Computer: mac G4 dual 450, 70gb Hard Drive, 448 RAM, Cubase VST5, 
VST instruments and effects (ProFive, PPG, Model E, Jx10, Battery, Attack, 
Absynth)

Studio Gear: Behringer 2004 Eurorack mixer, Midiman 2x2 midi interface, 
Electrix FilterFactory, Behringer Virtualizer Pro, Zoom 1204, Equitek studio 
mic, Danelectro Danecho, Fabtone.

Gutiars: Yamaha accustic, Fender Jag-Stang, Fender Jazzbass.

There is something about my Poly8 that i just love and try to find a place in 
most songs for it. I have this continuing desire to mod and tweak it. Maybe 
cuz the casing is so cheap feeling and it just seems like it doesn't matter if i 
hurt it. Anyway i have added Filt Cutoff and Q knobs to the front and just pu 
the battery in it (it must be an early MK1), the power source has probs too, i 
took it to a repair place but they couldn't fix it, so i just soldered a wall wart 
to the main batter connection. Works fine.

Hear is my question. The knobs work fine, but they only make an audible 
change to the filters from about 50%-100% opened up.. the rest of the range 
does nothing. Is there something i can do to make them sweep all the way 
across their range?

other question: That firmware problem is a real pain, it wipes half my presets 
when i go into Cubase... Is there a work around for this or do i just need to 
get a new Poly800?

Thanks in advance.

if anyone has other mods that they have performed or have ideas for some .. 
let me know..!