Tube or Amp Problem? Please help.

will it sound bad if I replace the 2 on the side w/ the bad tube with something else? 

Probably not but it might sound different on each side. I saw on the web that those tubes might not be very robust and you have around 1000 hours on them. You can change just a pair but if it was me I'd get a matched quad and start fresh. When you bring the bias to spec and everything adjusts normally, chances are the amp is fine. 

Ref: Upscale has Gold Lions for $92.95 each and Electro Harmonix for $45.95 each, no charge for matched quads.

Do you have a spare EL34? You really need to see if a tube will bias in that slot. It's possible you'll need a new resistor. Better to find out before buying a new quad and not being able to play them.

lowrider57, I am not home now but I will check. If I do I will definitely try it out. Hope I do but unfortunately I don't think so.

russ69, thanks for all of your helpful comments.

I agree.   Try a different tube.  Tubes that do that have an internal short or something that made it have a fireworks display.  
 

hopefully a new tube on that position will bias fine and sound will return as normal.