An equally valid assumption is that modern JIT manufacturing techniques are in place at Salisbury.
So working with PCB suppliers, that hold the layout designs and make boards - on request from Naim - in modest batches (maybe 20-30-40) at a time. Naim then populate boards and assemble into finished items.
But, in any case, even allowing for a renaissance with SuperLine, past 12 months, doubt if they make many more than 20-40 in a year. So buying boards for this item may well actually be on the scale of 20-30-40 boards, as and when required.
The JIT philosophy requires that inventory is kept to a minimum and stocks are not held if not required.
Triggers are put in place for stock levels, so when stock reaches a certain level, say just 10 left, an order is placed for another 40 boards. (Maybe even go into a larger order - with other boards - to get better pricing across a larger volume with the PCB supplier).
Beyond EOL, an item goes into “service life” and the Naim service dept still continue to source boards and components in a similar way. That’s modest size batches to suit forecast needs.
In the specific case of SuperLine, it is still a current item in production. So a supply of the main PCB will not be a factor in this current situation.
If you look at the inside of a SuperLine, it’s remarkably simple. The simplicity is part of its appeal. It has a main PCB board, connected to the various external terminals on the rear panel. Also secured to a brass sprung chassis. It’s comes off the chassis with a few fixings.
The topic in discussion - here in this thread - is the difficulty replacing key components, maybe 30+ capacitors, without damaging and replacing the main board. Which has 100+ components and all the wiring loom attached. So the main board is all the electronics part of this product. There is also a significant mechanical part, quite a lot of material in sprung chassis and its casing, etc. Mechanical damping and isolation is part of its design.
Surely the solution is to offer the customer a rebuild, or to replace the whole board, at a reasonable cost. Surely that is a more mutually beneficial outcome for both parties.