Korg Poly800/EX800 Users

I just started experiencing this problem on my EX800:
After being on for anywhere between 1/2 an hour to 1 hour, the left(mono) output
cacks out. There is almost no output and what is there is distorted. When I
wiggle the cord at the jack or pull it out and re-insert it, it makes no
difference. No crackle or anything. If I insert into the right output, it's
fine. I did kind of trip on the cord a little just before it started happening,
so I thought maybe I cracked a solder point, but with that senario, I would have
expected intermittent output when wiggling the connection.
I'll check for a solder crack anyway, but I'm wondering what else it might be,
if it's not that. The unit was also in a fire about 5 years ago. Any wise
thoughts on this?
  Thanks,
             Shayne