How to remove these return/inlet covers?

[exarkun]

My pool has in-floor return/inlets. Recently, I have something consuming my chlorine (not passing OCLT) and after follow SLAM for quite some time I'm planning to remove both my drain and return covers this weekend and ensure it is clean under them.
For the drain covers, I know I can turn off the pump breaker then remove the screws holding them on.
For the return covers, however, I was able to remove the retention screw from each of them but can only get one of them to screw out of the fitting. Is there any type of tool or method anyone is aware of that could be used to break these free? Even regardless of the SLAM, I want to adjust the flow to each of them.

For reference, attached is a photo of two of them (there are 4 total), circled in red.
Here is the pentair product: Pentair - Replacement Floor Return Fitting - Floor Inlet Complete - White

 

[Mdragger88]

Here’s a closer pic- maybe you could call the number & ask. Sorry I’m not better help..

 

[Mdragger88]

Also, lemme tag a couple guys
@1poolman1
@AQUA~HOLICS

 

[AQUA~HOLICS]

Sorry but I’m not familiar with that style of cover.

 

[JamesW]

 

[JamesW]

Use an adjustable pin spanner wrench.

The pins fit into the holes and the plate unscrews.

 

[JamesW]

 

[JamesW]

Make sure that the pins fit the holes.

https://www.amazon.com/Grinder-Adjustable-Spanner-Lock-Nut-Grinders/dp/B07FPGVXTQ/

Adjustable Pin Spanner Wrench

Amazing deals on this Adjustable Pin Wrench at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[JamesW]

Needle nose pliers can sometimes fit into the holes.

 

[Mdragger88]

I was thinking two phillips screwdrivers (or any with a round shaft that will fit) then try to twist gently without messing up the holes.
Lefty loosey I presume.

 

[exarkun]

I tried a needle nose but never thought of the spanner wrench! I'll give it a try, thanks everyone.

 

[JamesW]

Don't use excessive force because the plastic might break off.

Try to rotate gently back and forth to break it loose.

Most likely, there is sand or plaster in the threads causing the threads to be obstructed.

 

[exarkun]

Just to update, I was able to get them off. I purchased this tool as it had a wider opening than many similar and it worked great.

Amazon.com