T-Rex Tremster noise problem

[Mbas974]

Hi I have a problem on T-Rex Tremster tremolo.

when the effect is not on there is lot of noise...
once activated there is less noise, but still present noise...
it seems to be related to the volume pot, when rotating it the noise move from min to max.
Here a video better explaining thw issue.

What it could be ?
How can I check it ?

Thanks a lot in advance.

Here a video better explaining what the problem is : http://youtu.be/2M7DjhcEzJE

[anotherjim]

Sounds like either a ground connection is broken or the input wire to the circuit is.
You need a test meter that can measure continuity (resistance).
I assume you've checked the cables and are not using any TRS (stereo/balanced type) cables.