One channel pre dead, one source only

I've only got one channel live when I use FM. It swaps when I swap the FM outputs, so it appears to be in the pre (BAT VK3i). Seems kind of wierd that only one input is involved. My nearest BAT dealer is a 1.5 hr ride away, so I'd like to have some clue before I bring it to an independent technician. I will email BAT after the holiday weekend, but wanted to know if any of you folks have any ideas?
hmmmm. i know you know what's what, so this does appear strange. i assume you've swapped ic's (could be a loose/broken solder joint in the terminations). i also assume you've swapped inputs, if possible, for the tuner (a way to check, of course, whether the "aux" or "analogue" circuits of your bat are functioning properly) and, finally, that you've plugged another source into the inputs used for the tuner ( a way to check, as you know, whether the tuner is somehow the source of your problem). if you've done these things, and others that come with your known terrain, and still can't figure out what's happening, then neither can i. perhaps sean or others can chime in with more technical erudition. -cfb
OK, I swapped out the BAT for an ARC SP9MkII I have hung onto for an office system (glad I didn't sell it to help finance the Vandy 3a sigs I've been lusting after). Everything is fine now, so it seems to be in the BAT line stage somewhere. I will put it back in and check all of the line inputs. Unfortunately, there is some kind of imbalance in my listening room that tilts the balance somewhat, and there IS some crosstalk into the dead channel. These factors complicate things. The ARC has a balance control which I do have to tilt over slightly; the BAT does not. I'll report back later- any new thoughts greatly appreciated.