Hi Lloyd
I may have misunderstood what's happened but looking at your picture I think the bottom yellow dot (S3)? and the left hand red arrow (P1) are both connected to the ground plate.? I've also looked at the schematic and that is how it is supposed to be.? So it is correct to see continuity between P1 and S3.? Its likely that all is well.
73
Peter
Peter GM0EUL