How to remove these spa drain covers?

[JamesR]

In the attached spa for our pool, there are these two drain covers shown. Each has two stainless phillips heads screws. I removed the screws but the covers will not budge. Are they typically sealed/glued in place as well. I tried prying hard from an edge to the point where it feels like I will crack one. What’s the trick ?

 

[Rocket J Squirrel]

They should not be glued, but if they were installed before the plaster was cured, they could be stuck for sure. You may need to take them apart in pieces and replace them. Why do you feel the need to remove them?

 

[JamesR]

When the pump pulls 100% from the spa I get a huge about of air in the pump basket. I want to have a look at where the pvc plumbing attaches to each drain. Looking for a hairline crack or some separation.