Quoted from LTG:Ops often did things to lessen service calls on location games. One local op years ago would unsolder every wire to every coil lug and put heat shrink tubing on the wire, solder it back on. Then heat the tubing.
Rarely had a wire break off service call.
This seems like an attempt at the same thing. Only easier and less time consuming.
LTG : )
I know an old operator who told me he had to do that on every solder connection on some of the earliest gottlieb system 1 games when they first came out since they kept coming apart on a regular basis.