any body out there having trouble with Furutech XLR Balanced Cables locking into place ?

Hello, I was hoping to use this forum to ask the question, I can not get the Furutech XLR Balanced cables to lock into place on my now vintage McIntosh MC-501 Mono Blocks Balanced input! it comes close but just wont lock I wonder if it's introducing random noise into my system that seems to come and go , the noise sounds like a old preamp volume control that is dirty when you move a dirty control knob back and forth, I need to use the Balanced input on the Mac because I own ARC REF 3 Preamp that needs 20k ohms or more to sound ok , those same Furutech CCA cables work fine with my ARC and my Oppo/Modwright 205 the two sets of cables and a Umbilical cord from Wywires are the only changes I have made , thanks for any help