This beast will certainly not win any 'ease-of-serviceability' awards, at least not for the mode and range switches. It seems that they start with those and then build the rest of the meter around them.
Here is the chassis with the outer and inner top and bottom covers removed (four screws and one screw each, respectively), and the front panel (four additional screws after top and bottom outer covers are removed) disconnected and taken off. I left the boards that were hooked to the input jacks (four of them) connected and removed them as a unit. The black and white leads visible at front left are the rear analog input connections; they too connect to the front panel jacks but as the cable is fixed to the chassis, I disconnected them to remove the panel:
Boards and front panel:
Left to right: AC Converter, input buffer, ohms converter, and millivolt converter PCBs.
Here is the display/interconnect board assembly removed from the meter chassis (four screws in the bulkhead, and two more at the rear adjacent to the edge connectors, along with two wires to the power switch:
Front oblique:
Rear oblique:
Note that the display board is directly above the switches, supported on standoffs that also hold the bulkhead with the card guides on it. To make matters more difficult, they do not appear to be easily separated - in the 'front' photo, note the long, low grey connector visible just behind the two rightmost nixies and the small daughter board with the trim pot on it. Its opposite end can be seen in the 'rear' view just below the card guide bulkhead, beneath the guides second and third from the left. This is the ribbon cable that ties the display board to the interconnect board. On my meter, at least, it is about 4-5" long, and those are IDC connectors that are soldered to each of the boards. The display can be removed, but it will remain attached and flopping around.
I suppose for easier access to the switches, the standoff screws could be removed and the now loose display assembly moved over the edge connectors and laid on its back, then affixed to the two rear mounting points with small two hole brackets and the screws that previously held it to the chassis...
Closeups of the switches causing neo grief are below - the mode switches that are giving him trouble are soldered to PC boards both above and below. They solder to the interconnect board on the bottom, then have a small board with the mode indicators soldered to the top. NOT easy to clean, alas.
:
I'll see if I can further disassemble things tomorrow, and get some more photos up. Other photos of the meter are at:
https://pmanning.smugmug.com/Electronics/Fluke-8200A-Digital-Voltmeter-Pat