Hayward S310T sand filter Vari-Flo valve not seating on filter tank

[Neo5bass]

My first question is does the vari-flo valve fit into the lateral center pipe or does it slip over the outside of the center pipe?
Does anyone know the proper height the top of the center tube is from the top of the tank where the valve face meets the tank top?
A former pool guy told me he had trouble getting the valve off because I wanted to deep clean my sand and I suspect he lifted the lateral assembly too far off of the tank bottom trying to get the valve off and now I cant
get the valve head to seat properly on top of the tank. It's about 1/4 inch too high to mate.

 

[Texas Splash]

The MPV valve slips down & over onto the center pipe. I don't know the "exact" distance from the lower hub assembly to the top of that pipe, but it does sound like the tech may have lifted the center pipe and laterals up ever-so-slightly, thus preventing you from getting the MPV back on properly around the collar. You may need to have the sand removed enough to where you can ensure the lateral assembly is all the way to the bottom of the filter base. On some occasions, an owner can try to (carefully) push the garden hose back down there to soften and flood the sand enough to allow you to (carefully) wiggle or manipulate the lateral assembly down a bit, but you have to be very careful with method as to not cause more problems. In the end, you may have to empty and start over.

 

[sktn77a]

If you push it too hard, you'll probably break the laterals. You can either get all the sand out and make sure everything is at the bottom of the tank or cut 1/2" off the top of the stand pipe with a Dremel.

 

[Neo5bass]

The MPV valve slips down & over onto the center pipe. I don't know the "exact" distance from the lower hub assembly to the top of that pipe, but it does sound like the tech may have lifted the center pipe and laterals up ever-so-slightly, thus preventing you from getting the MPV back on properly around the collar. You may need to have the sand removed enough to where you can ensure the lateral assembly is all the way to the bottom of the filter base. On some occasions, an owner can try to (carefully) push the garden hose back down there to soften and flood the sand enough to allow you to (carefully) wiggle or manipulate the lateral assembly down a bit, but you have to be very careful with method as to not cause more problems. In the end, you may have to empty and start over.

I pretty much arrived at the same conclusion. Thank you for confirming it goes on the outside of the tube.