EAR 834P Problems

Hi folks- this is my first post here, so sorry if I don't provide all needed info. I'm having some issues wit an EAR 834P I acquired used about a year ago but am just now getting setup for good.

When using the HI FI news test record, on the first track which identifies the left and right channels, my channel separation is terrible. Ie, when he says the sound should only come from the right channel, it is also coming from the left channel and visa versa. I checked all wiring, and isolated it to the 834P by bypassing it and using the phono preamp on my marantz pre. Channel separation is perfect using that phono stage. Any ideas where to start??? This 834P has been modified with big yellow hovland caps and I think some different tubes. It's not in front of me right now, but I can get any information if that helps. My system is VPI classic 3--> sumiko blackbird--> EAR 834P--> marantz 8801 pre
Thanks for any help!
Make sure you have the EAR on the MM setting, not MC. Also, make sure you connect the EAR to a regular input on the Marantz, and not the phono input.
Yeah thanks Zd542- I had the 834P plugged into the CD input, so I know that's not the problem. The issue was apparent also on both the MM and MC settings. Could it be a bad tube?
"The issue was apparent also on both the MM and MC settings. Could it be a bad tube?"

How much difference was there going back and forth from MC to MM? Even if there is no problem, the MC setting should sound really bad compared to the MM setting. Did both settings sound pretty much the same?

If you have the volume control option on your ear, try it on some different settings and see if that helps any.
It is possible that the mods have caused parasitic capacitive coupling between the two channels in which case a tech will need to have a look at it.
Yeah , thanks. I have a buddy who has another set of tubes that we're going to try just to see if that fixes the issue. If not, I think having someone who is qualified look at it is the correct route to go-- I will most likely send it to EAR-USA and let them have a look. I'll post what solves the issue when I find out.