Mercury M72s Channel Bleed/Crosstalk Issue

My Mercury M72s dual mono preamp has a weird problem...Using the mic input, channel one is faintly bleeding into channel two, but not the other way around (channel two does not bleed into channel one). I've eliminated tubes or patch bay wiring as the issue. It is a dual mono unit with power regulation on each channel, and David @ Mercury said it's not a regular issue and didn't really have any advice but to send it. Of course, shipping alone to and from California would be $150 so wondering if anyone had some ideas to try first

Greetings,

Can you take a picture of the inside? Thinking it could be a lead dress issue, but can't be sure.  Is your unit built from old German modules?

Regards, Jim

I would check power supply caps on channel 1.