Mine was the same way! couldn't get it out, got mad, took a break. When I came back I used a small flat head screwdriver to get one end up and used another to pop it out. I celebrated with a cold beverage, Lol!

 

I just did mine. After removing the intake tube, it took me less than a minute to pop out the snap ring. I just used one small headed screwdriver, got it under the edge and twisted it out, set it on the ledge got another bite and worked my way around. Mine was easy.

 

X2 took me no time at all