+1 got the paper tube idea, fixed the dented cone on a project speaker i'm working on the first shot!
try the vacuum method
Bubblegum, worked for me.
Vacuum did not work, gaff tape did not work, sticky anything did not work. Only the small pin hole and paper clip worked for me. Very stubborn dust caps.
Pin hole and wire works for me. That hole can't be seen with the grill on or off really. Only perfectionists refuse to poke a hole in the dust caps.
I use to be a perfectionist but life has worn me down and I accept and live with alot now that I wouldn't have 25 yrs ago. :D
Now where's that needle.....;)
As far as the dust cap fix.. I have used a shop vac and the needle trick .. both work well ... the pin hole should not affect performance.. over time if enough dust gets in them maybe. even then I doubt will affect performance.