Cleaning Bathroom Ceiling Exhaust Fan

I just moved into an apartment that has Nutone exhaust fan/light combos in the bathrooms. They look very dusty and I doubt they've been cleaned in the 10 years of the building's existence. Removing the plastic light cover is easy, but I see no obvious way to remove the "grille" cover part to access the fan underneath. My laundry room has one without the light that has the traditional "squeeze clips" on each side that you can pull down, but I see nothing of the sort here—just some impossible-to-access screws that attach to the light ballast.

FWIW, based on what I could turn up in searches, it may be the original variant of model QTREN080FLT, but it looks like they eventually updated that model to one that uses normal clips to get the cover down.

Does anyone here have any suggestions on how to gain access to this thing? Pictures attached.

Thanks!

 

Took one more picture with the light cover off; maybe that might help?

 

The only fans/lights I have seen all used the V shaped spring clips you mention!

They may be there but holding tight!