If you have a multimeter you could do a continuity test on the snaics.
How much of this system is 2nd hand?
Worst case scenario you can get the whole lot checked and serviced by Darran at Class A in Sheffield (if you are in the UK).
New snaics can be ordered from your friendly naim dealer, assuming 1 or both snaics are faulty. Or get them reterminated possibly.