It could be a faulty lead or plug or possibly socket into the card.

If you have a multimeter (at least that's what we call here in Australia) - it's a electronic device for measuring resistance, current, voltage, etc., just set it to resistance and see if you have damaged leads or plugs.

As an example: if it was a lead with 6.5 mm mono plugs at each end, you'd touch one probe on the tip of one end and the other probe on the tip at the other end. You'd then repeat this procedure with barrel one end to barrel other end. In both cases you should get near zero resistance. The last check would be barrel one end to tip the other end. In both combinations of this, you'd expect to get infinite resistance.

Any resistance reading other than the above would indicate faults.

MY SONGS...
Audiophile BIAB 2025