Discovery LXE 40M. 2021. Trying to remove the plastic louvers for the AC returns to get to the 5 inch filter to clean. Is there a trick to remove the louvers? I’m pulling down, prying with no luck. Am I just not pulling hard enough?

We do have Coleman units but not that style. We have 4 - 6” circular returns per unit. I’ve found that they pull down but with a good amount of force. There are 3 “tabs” that hold the grill in place. I found that getting fingers in between the louvers, pulling down while pushing on the outer edge will create an angle to release the one tab. After that, the other 2 tabs will release fairly easy. 
Thank You for responding!