The places circled in red show the damaged places on the board where the mounting tabs for the case originally were. The last person to work on this unit was able to re-seal the box with solder but I won't want to do it that way again as I don't trust the grounding with those missing tabs.
Here is the component side of the board with the thermal tape removed. The restoration task will be to replace the 22uF electrolytic capacitor to a 105°C, high reliability type. Also the 1uF tantalum. Following Beolover's lead I will also replace the two oscillators for the processor ICs (X1 & X2). Those will require changing two capacitors on each to new ones that match the new oscillators (18pF). Last, I will also reflow the solder joints on all of the connects and board vias as those have been known to have hidden problems.
CAUTION: As Beolover noted in his Beomaster 8000 restoration, messing with the crystal oscillators could be a risk to the two processor ICs (IC3 & IC4). As a safety measure I shorted the two oscillator leads together and removed the processor ICs from their sockets (using an ESD grounding strap of course). With IC3 and IC4 safely out of the way I performed all of the rework to the board.
The result is not the prettiest thing (rather ugly really) but it is solid and works. The copper straps securely keep the box together and I can measure good ground continuity anywhere on the board. If I have to do this type of repair again I think I will apply strips of copper to the lid pieces first (to use as solder pad anchors if you will), then tie the bands in with those anchors.
Removing the assembly should be pretty easy. I didn't solder the copper straps on the sides where the top and bottom pieces meet. To open this box up again I only have cut the straps along the sides, de-solder the two main ground straps and the box will open up. In the picture below I marked the cut points with the red arrows. Note the green arrows. Those show the previous repair where someone fixed the broken ground connection by scraping away some board coating at the ground plane and soldered that right to the metal housing. While that should work I think it is risky because it is susceptible to the solder joint cracking if the metal box is stressed. I like the straps better because they provide a much more reliable connection to the ground plane of the board. The grounding strap also has a little give in it so it can withstand any movement.