Reverb Feedback Issues SOLVED

[makinrose]

I've been having problem with new build. It's essentially a Deluxe Reverb Combo but with some added decoupling and improved grounding. The issue I'm having is with the reverb tank.  Outside of the combo the reverb is quiet and operates as it should. When placed inside the combo the reverb starts to feedback building into loud howling.  Moving the tank around, flipping is orientation,  and padding the reverb bag really hasn't helped at all. I've tried a few different tanks and am at my wits end about what I'm doing wrong.   Any ideas?  Thanks for everyone's help!