doesnt the dust cap help pull and push air across the voice coil gap wich is semi vital to help cool off the vc when the sub is playing.... ?
I imagine some subs are designed to work this way, and others are probably not
but - it seems like a bad idea to me to bump hard with missing dust caps as there would be far less air movment across the vc area to cool things down like this.
what about gorilla glue? im in the same boat as the op. but i opened my dust cap because i thought i heard a clicking noise so i opened it and it was all in my head lol. but now i need to put something over the hole. and yes that makes sense if you dont have the dust cap then the heat created would lower power handling.