Went to record on my 688 tonight and track 7 isn't registering any input at all, from both mic and line inputs (with the appropriate scene for each). Other 7 tracks 1-6, and 8 are working fine. Any ideas on where to start looking? I had this thing taken apart last year and I fixed and tuned up the deck, but I haven't dealt with the mixer section at all. I'll start with a signal from my siggen going in and trace the audio, but given the routing is handled digitally, I'm not sure just how far I'll get. Any suggestions, etc appreciated! EDIT: the gain LED does light up with audio coming into the Mic input. If I crank the gain all the way up I can hear a very quiet portion of the audio coming in. EQ does seem to have an effect on this as well.