Can a 554C Subset Be Rigged to Work With a D1?

[unbeldi]

.

[rp2813]

No, the red and yellow mounting cords are indeed switched for the sidetone fix.  Red is now on L2Y and yellow is on R.

Somehow, switching the line cord's L1 and L2 leads made this sidetone fix effective instead of rendering the phone completely dead.

As a follow-up, the ceiling fan apparently isn't the source of the hum.  After putting the subset back where it has always been, the hum returned even with the fan off.  I've moved the box back to the spot where humming is eliminated.