I've found that hot glue doesn't stick to plastic surfaces all that well.
I have found that surfaces that are shiny composites often need roughed up first to give some "tooth" to them and then a good quality hot glue works just fine.
That roughing an be done with a rough sandpaper, or an Xacto type knife making a few surface cuts in an X pattern, just in the area where you want to apply the hot glue.
"Good quality hot glue" - I have also found that there are differences in formulation of this stuff, as well. For example, there are low heat hot glue sticks designed for low level "pasting" that don't work very well in the electronics repair scenario. But there are also pro grade sticks with typically higher melting points, harder composition when set, that work very well indeed.
Silicon RTV can work very well for something like remounting a cracked or broken meter hold-down, too. Care should be taken to find and use an RTV that does not contain Acetic Acid, which can interact with solder joints in electronics. These exist and state same on the packaging. Rule of thumb, if the RTV smells like vinegar when opened, do not use it around electronics.