Well, he may have attempted to correct the problem in an unsafe manner…

 

I have had to repair installations in which that removable jumper strip between the two outlets in a duplex outlet had cracked at one of the separation crimps. Quite a subtle source of problem. (folks in the UK will not know about this, UK pout;ets are totally different.) That fault mode can cause very strange problems in outlets not in the same area, and be a real puzzle to track.

 

Indeed. But those magical fixes do not always last.