Securing mod wires to PCB
At work I use Dow Corning 3145 RTV silicone adhesive for this very purpose. We also use it to secure flex cables in their connectors, secure right-angle parts such as capacitors to the board surface, fill small gaps to make the product waterproof, electrical component insulation, and so on. It is chemical-resistant, water-resistant, corrosion-resistant, non-conductive, and sticks to just about anything. There are many different uses for it, and in my opinion it is absolutely indispensable. 



And to prevent this from being a specific product plug (I am not affiliated with the company in any way, I just like the product), I will say that just about any silicone adhesive designed for printed circuit board use will probably work great in this sort of application.