I heard people were having that problem on the Blade CX also. (I never did) If I recall, they were CAREFULLY using a drop or two of CA. (Super Glue) on the edges to hold the tops on. Like I say, I never had that problem personally, but I'd make sure you either get a medium CA or 'Gel' Super Glue so it doesn't seep where you don't want it...

Search the Blade CX forums and you might find the answer there too.