NAIM NBL - Service Issues & Fault Investigation; 3.1 In comparison to many components in a hi-fi system the loudspeaker is fundamentally a simple device. In any case of suspected loudspeaker failure it is important to be certain that the loudspeaker, rather than another component in the system, is actually at fault. A simple procedure of investigation by the substitution of known good items in the hi-fi chain should reveal the true location of any faults. Always be aware however that a faulty power amplifier may damage any loudspeaker subsequently connected to it so be sure of the amplifier before connecting a good loudspeaker.; 3.2 Faults with NBL are likely to fall into one of three categories:; NBL Disassembly and Reassembly