Bartolini Preamp problem

I install the new Bart preamp and everything works perfectly outside the bass. However, when install the treble pot, it shorts out the preamp. If I leave the treble pot outside of the control cavity, everything is normal. As soon as it touches the shielding paint, the preamp go crazy. It's starts cutting out and the treble acts like a volume pot. I'll include a video.

 

Ill explain a little more. I took a bass/treble stack and installed two separate pots. I've tried 3 brand new pots on the treble with the same results. But when I reinstall the stacked pot, it's works normal. Are stacked bass/treble preamps not mention to be changed?

 

Ok. I think you're right. Out of the three new pots, it seems only one is doing that. I just tried the others and all is fine. Here is a pic of the bad pot.

 

I can't really see what's going on inside the pot.

 

Thanks man. I checked and like a micro strand was touching the body. I fixed and reinstalled and it's working.