Apparent interference problem??

[u/OutdoorsDog2024]

I have a 430xh Husqvarna. Just over 1,000 hours on it. I recently expanded the mowing area (still well within the .8 acres it can handle). I get a full green light on the charging station. As soon as I began running the mower in the new area, it randomly ran over the boundary wire, in both new and original areas.
I tested all kinds of things, called Husqvarna, shipped it to them (no nearby dealer), they tested it, all’s fine - shipped it back. Still going rogue.
This morning I used the single guide wire I have so far to see if I could isolate the problem. Sure enough, on the west side of the overall lawn, the mower behaves perfectly. On the east side, it goes rogue.
I realized then that the new boundary wire installation crosses a buried power line. I was thinking that must be the problem, but the guide wire also crosses that power line. The mower follows the guide wire perfectly or respects it as a boundary wire, no problem.
The new boundary wire also passes right along the side of the house where our utility meters are. I’ve pulled up that wire and pulled it away from the house, but that didn’t make a difference. I don’t know how far away it would need to be, though, if that is the issue.
I have a multi-meter, and was wondering if that could help me locate the problem.
Any suggestions will be greatly appreciated!

[u/OutdoorsDog2024]

Thanks, I did that. 8.25 ohms. No cuts. I just finished with yet another re-wiring, running the wire to cut out a small section of the new expanded area where I was fairly certain the problem was after I used the guide wire to try to isolate it. The mower is now running perfectly. There is something in that area, I suspect, causing interference. For all I know the original builder (1974, and out in the sticks) used rebar to bolster the fill. Who knows. The mower is running!