Help! pump cover keeps falling off into my tank

I have an extra small pump now for extra flow in my tank since I have coral now. 
The problem is it starts shaking and then the top that covers the fan part keeps falling into my tank at least once a day sometimes multiple times a day.  Wouldn't be so bad if those darn clowns didn't keep biting me everytime I reached in to get it out  Darn Nemo movie,j/k, had to get some clowns for my 2 year old!!    Anyways any advice on what to do?  Is gluing it ok or no, duct tape?? 

 

thanks everyone for the advice/DesktopModules/ActiveForums/themes/_default/emoticons/cool.gif  There's always so much good advice it's hard to pick one  I've got a friend whose gonna try and work on it for me.  Some sort of magnet thing.  If it doesn't work I've got some good options from ya'll to try.
Thanks again