[Antennas] Hy-gain AV-640 issues

Sat Apr 23 19:36:24 EDT 2011

My AV-640 vertical has worked beyond my expectation for several years, but I recently hooked up a new rig to it (my old rig died and the antenna hadn't been used since early last year).
When I first installed the AV-640, I was able to tune it to less than 2:1 over most ham bands, a little less on 40 meters (I didn't save the data). Now it has a very high VSWR (>>3:1) on all bands EXCEPT for 6 meters, which has a VSWR of 3:1 or less across the band. If the coax or matching circuit (which I recall is a balun plus a current choke) were bad I would expect that 6 meters would show the effect at least as much as the other bands, but it looks like what I would expect from a properly-working antenna.
Has anyone else seen this or have a clue as to what the problem might be. I haven't taken it down yet and I think I can remove the matching circuit without doing so. I plan on doing that soon if I can't find any other places to look.
Bob, N7XY