HP-27 Repair/ACT/Panamatik LP?

[Zaphod]

The 'chip' on the 466 chip looks to me deliberately done , at manufacture time.... and not a 'chip', but filed (by a round needle file - by the looks of it) to electrically disconnect the lid/cover from the lower level connection to the inner substrate.

The wire also looks like a post-production addition/mod.

If a via is broken it could be fixed by inserting a very short wire strand (tinned) and soldered so the solder draws in through the via and reaches both sides. One would have to be careful to ensure the length of wire.