Wierd Phono problem - what causes this?

Playing a couple records tonight, after a couple weeks not using my TT, the left channel is very bright and irritating sounding, and the right channel is not bad, but very rolled off on the high frequencies. They don't quite average out - the overall sound is harsh and aggressive. Plenty of bass from both channels. I am using a Dual 616Q TT, Adcom crosscoil HO MC cart, and JJtube phonostage, plugged into my DAC/Preamp. CDs sound fine, so it's not a problem with the DAC/Pre, amps, or speakers. It was sounding pretty good the last time I played it. The cartridge does not seem loose, and I don't se any obvious damage. Any suggestions?
Flip flop your tubes left and right..Maybe a tube???
I'll bet your right and left channel + & -'s are reversed in some fashion at the cartridge.
Is the cartridge mounted correctly?
I had a very similar problem,which took alot of time to diagnose.In my case,it turned out to be a phonostage problem,which is being fixed,as we speak.This sounds like your situation.

The actual reason for my own problem,was something that could have easily been avoided,if I had a dealer(who sold me the "reason" for the "issue"....a long story)who cared about a customer's satisfaction,beyond the quick profit being obtained.

Much aggravation later,and I am on the cusp of getting back to where I belong.

I hope you can diagnose the problem without too much angst!

Good luck
Thanks for your responses, all. I just gopt through playing around with it, and it seems to be a phono stage problem. Switching R & L cab;es coming from the record player into the phono stage didnt change anything, but switching the phono stage output cables at the phono stage caused the problem to change channels - now R side is bright and aggressive. I switched the tubes, but this didn't seem to have any effect. Ths condition is the high frequencies are a lot louder in the L channel than the right - panning the balance control right to left, the right channel sounds pretty good, but the high frequencies get a lot louder panning side to side, so it doesn't sound like the lows are getting attenuated. I think I'm goiong to write to the manufacturer.