Amp troubles.

So basically, the channel switch popped out of place on my Peavey Triple X head. I unscrewed the switch to see what it popped out of exactly and i can see what i have to do, my problem now is that i can't access the "part" i need. It's just a matter of slotting a small rod into a small hole but the part i need to slot the rod into is loosely spring loaded so i can't get a good grip on it and even if i could, it's too far inside the amp to really work on.

So what i need to do is open it up slot it in, close the amp and screw the bolt back on and it should be grand. I haven't the foggiest what part I'm ment to open though and I'm afraid to go opening up parts of my amp not knowing what exactly I'm doing.
I'd hate to have to take it anywhere for such a small job so i was wondering if anyone had any experience with these(or similar) amps and knew how to get at it?

I'll attach some pictures to give you an idea of what's going on here.

I can only see the front plate and the grill at the back as places to open but can't see how to get the the rest of the components through these panels.

Hopefully some one will know, i know some of you work on amps so I'm looking at you guys. :P

Thanks in advance lads.