Hello all!

I recently acquired an old Aspen hollowbody electric guitar. The neck pickup seems to play fine through my amp, but when I switch the selector to the middle position and the bridge position I loose signal. There are volume and tone controls for each of the pickups, which I have tried fiddling around with to no avail (they work for the neck pickup, have no affect on non-functional bridge pickup). 

I have been playing guitar for a while, but have never switched out any electronics or done any sort of repair. I would love to learn how to repair this myself but have no idea where to start. Does anybody have any suggestions where to start / how to diagnose the problem / if this is even doable for a newbie? 

Additional information
The pickups are humbuckers
I see no plate to gain access to the inside, I've heard this means I will need to go though the sound hole / input jack
I have a soldering gun but very little experience soldering
The guitar is pretty old, I'd say made in the late 80's

Thank you for your help! 
Ist step would be to get a multimeter a resistance reading from your pickups.  From your description it sounds like the bridge pickup is shorted but the only way to know for sure is to get a resistance reading.  Because hollowbody electrics are hard to get to I'd take the reading by plugging one end of a lead into the guitar and then use the multimeter on the other end.  One probe needs to go to the tip while the other probe goes to the sleeve.   Flip through all the switch positions and see what readings you get.  The bridge pickup should read as high or higher than the neck pickup.  When both pickups are selected the readings should be about half of what you get from the neck pickup on it's own.  I suspect you have a short in the bridge pickup but testing with a meter will let you know for sure.
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Probably  just a crapped out toggle switch. If it is the Les Paul type switch, that would be a more likely scenario than the pick up being bad. Really the only way to mess up the pick up would be to demagnetize it (highly unlikely), or the wires are damaged. 
pics of gear updated on profile 11/16/09
GOLDIE93 If the pickups were potted with bee's wax it can sometimes corrode the wire inside the pickup.  That is why I won't use bee's wax on my pickups.  Pickups wires can also corrode if you spill a beer on them.
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CorduroyEW  I did mention the possibility of damaged wiring and that could very well be the issue, but the switch would be the first place to start as it is far more likely.  the other option to consider before the pick up, is the volume pot. If it is not tightened down and able to spin around, the wires could have broken off the contacts
pics of gear updated on profile 11/16/09
^ I still don't think it would be the switch because if it were the switch it wouldn't be very likely to kill both pickups when in the center position.  It should only kill 1 of them.  The pots are a likely cause and so is a frayed wire but we will have a better idea when we find out what resistance readings the TS gets.
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