Cort:

 

I'd put the old balun back on as a test and see if the SWR goes back to the way it was.  That will tell you if it's the beam or the new balun.  If it's the new balun, I'd suspect "center conductor drift" where the center conductor has melted thru the foam and gotten too close to the shield.  Or maybe the RG-8 was old and contaminated with water.