Bug screen crud, keep 'em or cut 'em

[Phil-G]

Take the diaphragm off. so you can blow thru the slits
Make sure you keep the diaphragm on the top of the driver, so it drains out the horn
Use some Windex or Mr Clean or something.
After the gunk is soft. Use a small vac from below a small artist brush (be careful until you get most of is out)
from above to below to get to the gunk.
good luck