Sonic Frontiers Line 3 preamp issue

I have a Sonic frontiers Line 3 preamp. My problem is that both left channel single ended output connections only produce sound when reverse polarity is selected. When it is not selected, there is very low distorted sound with a buzzing noise. I retubed the preamp to emsure it was not a tube problem but to no avail. If anyone has knowledge of what could be causing this I welcome any and all informartion on what could be causing this problem. If not, would someone please recommend a good repair shop that would be able to know how to rectify this problem.

Thank you.
Sounds like a problem with the switch. It couldn't be the tubes obviously.
Get a hold of Chris Johnson at Parts Connexion after all he designed the product and still does upgrades & repairs to S.F. equipment.
I would suggest calling as email response can be quite slow do due how busy they get.
Toll free number: 1-866-681-9602
Direct emial address:

Good luck.
It's probably the switch, but, your description of the sound, sounds like a fuse.
When you say a fuse, you mean the one in the power supply? I can get a fuse for little to nothing and then try that first before shipping it out.
It can't be a fuse. If it was the power supply fuse, the preamp would not even light up. Take the cover off the preamp and look at the solder joint where the switch engages if you can see it. Also look at the left output connector from the inside of the chassis.
While, I still think it's the switch, sometimes a blown fuse will work erratically.