Restoring my Microbee

[ChickenMan]

Ooh I bet I know what the "soldering iron" scars are. Someone wrapped the tape drive in the power cable. There is a known reaction in uncommon cases between the plasticiser in the power cable (The additive that keeps the cable flexible) and the hard plastics in some computers.
You end up with "burn marks" around the systems. Most prominent in the corners.

Chesh

I can fully vouch for that as it is VERY common issue with System 80 when people wrap the power cable around the unit and put it in storage.  You end up with deep black groves on the case   You can scrape out and clean up the black but the groves remain.