Solphia repair

I was using a Solphia el-34 in my office system, and it seems to be down to only one channel. I have changed all the tubes, switched sources, moved speaker wires from one channel to the other, all with no luck, the problem is with the amp. The odd thing is before I lost the channel, I thought I noticed one channel was only putting out about 10% as much sound for 1-2 days before it quit all together. Is that possible? I live in southern Oregon and would just as soon not ship it all the way to the east coast for repairs. Any suggestions for a west coast repair? Is it even worth the cost/effort? Thanks for any help.