1.
The first thing I will discuss is the missing shelving from the cabinet. It was removed with some modest level of violence, either because it wasn't wanted or because it had become broken.
In A-V models with the Graduola, there is a bulkhead on the left side of the lower cabinet which creates a pocket between it and the sidewall of the cabinet for the Graduola cable to rest in when fully inserted. The original bulkhead which probably formed the left side wall of the shelving was probably damaged in the removal of the shelving, and a new one was fabricated out of some hardwood plywood, perhaps rotary cut maple. This work was done long ago. The plywood is of a serious grade that would be very hard to find now, and the good side surface veneer is so thick that it could be sanded till the cows come home without abrading through it. Also the screws holding it in are plain carbon steel and have a bit of rust on them. The work was competent but not highly professional. Whoever did the work here left their fingerprints in the walnut/ebony stain that doesn't quite match the colour of the cabinet - so if they have a criminal record ....

I spent yesterday morning repairing this repair bulkhead. The plywood had warped away from the struts that hold it away from the cabinet side wall, and the glue joints between the plywood and the struts had come loose in multiple places.
I could probably fabricate new shelving of some sort that would bear a superficial resemblance to the original - there are enough pictures floating around to model something after so that it would look similar with the cabinet doors open. The major difficulty now would be finding a good quality ¼" plywood that would stand up to use as shelving.
And the likelihood of finding an A-V being parted out with shelving intact by someone willing to remove it carefully and sell and ship it as flat-pack is slim to none.
So it is probably best just leave things as they are?