gimmie a minute
....
Ok, schematic says a 1.25A 5x20 fuse
top panel seems to come off on it’s own, two screws on the back, some on the top.
It might be the sides don’t even have to come off, but don’t quote me on that. the wood side panels seem to be wholly separate from the top piece.
IT looks like it might be, remove the side panels screws, slide the side panels back and off, then... look for side screw on that top panel that were obscured by the wood inset at the top edges of the wood pieces.
Then two screws at the back of the top panel. the two top screws, then any of the side ones for the top panel that the wood sides were hiding.
I've never handled one before but that is what the images seem to be indicating, when one looks at the complete unit.