how to fix ground loop him?

For the first time ever, there is suddenly a him in my system. Seems to have popped up over the last few days...not sure why? Only change was I moved some wires around to get at my DVR? Not sure where to begin to find source?
DVR, Cable TV.
The easiest place to start is to temporarily disconnect the CATV Coax cable from the DVR. If that stops the hum that means a difference of potential, voltage, exists between the CATV provider's shield of the coax cable and the safety equipment grounding conductor at the wall receptacle.

A digital ground loop isolator like the Jensen VRD 1FF will stop the hum if it is caused by the CATV company's coax cable. The isolator will not correct the grounding problem though.

Disconnect the CATV coax cable from the DVR. If that stops the ground loop hum post back your finding.
I rather have a HER in my system then a HIM any day....
Jim above is right, If his advice does not help, try to separate the CATV coax from the rest as far as possible and ovoid any wiring loops in your layout.
If it appeared when moving cables it might be a loose or bad cable. Systematic removing connects until you isolate the problem is usually the best method. Or remove all of then and plug them in one at a time. Tedious, but sometimes it is the only way.

I had a similar problem once and it took a long time to find. Turned out to be RCA connectors where the back of the connector screwed on. It was loose and apparently broke the ground. When I tightened it up the ground loop went again. I replaced all the cables of that type and have not had any trouble since. I would suggest you check all your cables.
Thx for all the suggestions. It will have to wait for a day when the back is cooperating and I can get behind the rack. My wife keeps saying its time to simplify the setup...sadly she may be right.
Schipo, A HER who HUMS would be even better........
Detlof love your of the old gold
Neither would I look into the ladies room to find the him, I
mean the hum.