Linn Ninka Repair or Parts or Common Issues?

I have a pair of Ninkas I bought in 2005 and they've operated beautifully.  However, one of them stopped playing the bass octaves.  The treble speaker sounds fine.  I removed the lower speaker to visually inspect the crossover circuitry and it looked ok.  Has anyone had any repair experience with these speakers?  

I called the dealer whence I purchased them and it was gonna be $190 just to diagnose, then repair.  I decided to return to my hobby from the '80s when I was an electronic hobbyist, which led me to my EE degree, which I never used. :-)

So I bought an oscilloscope from eBay and I am looking forward to troubleshooting it.  However, where do I get parts for it?  Or do I just need to content to discrete parts from Digi-Key?