I discovered recently a very convenient product, called "Plastic Dip", a Synthetic Rubber Coating. I used it on my T12FG to protect the soldering of the JETI module wires on the back of the trainer plug. According to the manufacturer website, Plasti Dip is a multi-purpose air dry, synthetic rubber coating that can be easily applied by spraying, brushing or dipping. Plasti Dip protective coating products resist moisture, acids, abrasion, corrosion, skidding/slipping, and provides a comfortable, controlled grip. It remains flexible, stretchy and will not become brittle or crack in extreme weather conditions
Plastic Dip exists in several color, dry in 30 minutes depending of the layer you apply. It also exist in Spay, but I have not tried. It is convenient for any application where a shrink tube cannot be used: On a surface, on a connector. It can be remove without trouble and without damaging parts.
Plastic dip is not cheap :(
About 17 euros for 100 g. But once again, this is very convenient, that's why I wanted to share the information with you all.
I found mine here.