I wouldn't expect physical trauma to be the issue, more something
like a metal flash due to an arc, or tin whiskers... Something
The damage to the resistors in the unit was almost certainly caused by
an electrical overload (the "trauma" to which I referred). Or, more
likely, to a number of overloads perpetrated by one or more clueless
previous owners on more than one occasion.
The other damage (disconnected wires, etc.) was caused by someone
hamhandedly attempting to diagnose or repair the original overload
damage, or contemplating harvesting parts from a unit they knew was
damaged beyond any practical repair.
The only cure is to replace all damaged resistors with new resistors of
equal or better quality. If they are in the oil bath, the complexity of
any repair is raised exponentially. Note that there are almost
certainly other damaged resistors in addition to the ones that the OP
As a practical matter, an instrument with damaged (overloaded) resistors
will never work properly again. The only 720As I have ever seen that
worked properly after damage of this sort were repaired by Fluke at
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