Mesa Recording Pre Tubes problem

Hello, I'm having problems with my Mesa Recording Recto Pre Amp, I started to notice the loss of power when I used the distortion channel (channel 2), the volume would drop a lot and come back to normal when I went back to the clean channel so I decided to retube the pre amp with Tung-sols (replacing the stock Mesa 12AX7) and the sound was better on the clean channel but channel 2 was muted, I wasn't able to get a sound out of it until I put back one of the old 12AX7 tubes in position V4. I thought it was a bad tung-sol so I tried all of them in that particular position and same result!!! no sound!!!.
Right now I have the Tung-sol tubes in the pre amp except for position V4 which has one of the old 12AX7 mesa tubes and the sound of channel 2 (distortion) sound very boomy, specially when I palm mute a chord, I tried lowering the bass on the channel but still is too boomy for my taste, even channel 1 (clean) sounds a little boomier than before.
Does anybody know why position V4 gets muted with these tubes? and why the sound is too bassy?, should I go back to the original stock tubes from mesa? before all this issue with the loss of power the sound was awesome but not anymore.
Hope you can help me clarify my doubts, thanks.

In case your problem has not been solved, I would just email Mesa and ask them. It seems only 5 people actually own the Rectifier Recording Preamp and since I'm one of them, your only hope is with the other 3 owners or Mesa Boogie themselves. :wink:

I've got very similar problem with my Rectifier recording preamp and its driving me nuts. On initial power up all is good, 5 minutes later and the sound drops out either on one or both sides. Then I change channel and its fine, then I lose sound again and I randomly get good or muffled sound for a few minutes. I tried to systematically test the valves but got conflicting results. Via the recording outs I can see the right channel is often down on volume. Heat does seem to change things as it warms up, the left channel seems OK.

It 'appears' to be related to the right channel but I've been debugging for months and changing my mind. Could it be capacitors aging or an output transformer?

I've tried emailing Mesa before and never get answered - I assume it's because I'm in the UK and they expect UK dealers to handle it.

Sadly my repair man has been out of action for nearly a year, any recommendations for repairs in Berkshire UK?