WINDSCREEN WASHER NOZZLES

[ERNIE.H]

HI ALL
MERCEDES C220 BLUETECH 2015 W205

Having trouble with drivers side (UK model) screen wash nozzle very little flow compared with the other nozzle's, I'm going to attempt a check on nozzle but can not figure out how to remove plastic cover on inside of Bonnet to get at nozzles. there seems to be 3 round plastic holdings that I'm not sure how to remove (or do I need to remove them as the cover looks like it will slide on theses fittings). See attached photo.
Don't want to go forcing something by not doing it correctly.

Any help would be appreciated

ERNIE.H