The best solution is a a Polyurethane caulking. These are routinely used to adhere large parts in power supplies to protect them from vibration. There are hundreds of varieties of Polyurethane, commercially available and a few publicly sold in hardware stores ( eg PL400). Your choice depends on your resources available to you for selection. Yamaha use a pure white compound, stiff yet not brittle. Cure times and hardness depends on VOC content among other things.
PL400 is cheap but messy but thin coatings dry in hours and cure in a day if exposed to air. I used it once to repair the broken brittle CPU plastic socket in an ASUS board, broken by the lever spring clamp. A little goes a long way good plastic qualities to retain shape ( not flowing or elastic) Older products with higher VOC content, cured faster and were more brittle. But lower VOC content is the trend for consumer goods. It is commonly used to prevent squeaks in sub-floors.
I am not saying this is the best for you, but to give you an idea what qualities to look for in an ideal adhesive.