Access Virus TI Keyboard, Buttons with strange behaviour.

I think I just got ripped of when I traded my fully working TI2 Polar with Access Virus TI Keyboard + $500.
I first discovered this two days after the purchase. And it gets worse.
The previous owner is a piano player and didn't seem to notice the faulty buttons. I can't make him reverse the trade.

Following buttons behaves Strangely:

Oscillator Section:
OSC 3 ON/OFF; Toggles on/off AND sends me to the Matrix edit.
Mono on/off: Toggles on/off AND sends me to the Matrix Edit.
Sync on/off: Toggles on/off AND sends me to the Matrix Edit.

Filter Section:
Edit Button: The menu just blinks so fast I can barely read what it says, but it seems to be LFO edit menu or Filter edit menu, it varies between the two.
Filt 1 Button: Toggles between filter type, but also sends me to the Store Patch mode.
Filt 2 Button: Toggles between Filter Type, but also sends me to Edit FX Menu.
Filt 1 Select button: Selectes filter 1, but also changes the transpose down 10 tones, as well as changing patch down by 10.
Filt 2 Select button: Selectes filter 2. but also changes the transpose down 10 tones, as well as changing patch down by 10.

I might not be that accurate because it's so much. And it keep changing. Earlier Filt 1 Button sent me to LFO edit. And it was only two buttons having problem at the beginning.

I've tried Software upgrade and downgrade.
I've tried to reset by pressing the ARP edit button before starting up.

None of this helps.

I'm not afraid to open up and replace parts or solder or measure voltages etc. But I need to know what to look for.
There are no certified Access Virus repair shop in Norway. I hope to avoid shipping it for service as it might be expensive.
Please tell me what I should do.

Zitat von Marc

there is hardly anything you can do. if you're really lucky, it is a weak connection in between the panel board and the rest. the button/knob matrix can malfunction when as little as one connection is not reliable. in this case a button pressed cannot associated correctly. this all can be caused by something as trivial as a failing resistor. it is rare but we had cases over the years. the challenge is to locate the component in question.
hth, marc

What do you suggest I do? Would a general Service station for other keyboards be able to figure it out without the scematics? Or am I bound to ship it to Germany? The dealer Procom who sell Access Viruses here just tells me to contact a "Roland, Korg & Yamaha" service station. Which seem to have little knowledge about the Virus.