Hayward SP problems...new to pools..

If it's easy to pop the top and easily peek inside go ahead and do it but it probably isn't necessary. I take my valve assembly inside every winter anyhow and, like Watermom, never had to do anything to the sand for 10 seasons. As for air leaks, any joint ahead of the pump inlet can be suspect. All it takes is a tiny place for air to be sucked in. You can take something like petroleum jelly, vaseline, and smear it around any suspect joints. Much cheaper than silicon grease. If you locate something then we'll deal with fixing it. When done, wipe off the lube and clean any residue with alcohol, paint thinner, or anything that will clean off the lube and evaporate. Anoither source of air could be low water level and you get a vortex in the skimmer and momentary suction of air. You should be able to hear that though...pretty loud.
That's it for now.
Al

Thanks for all the details....today is pool day for me, so i'll go thru the suggestions and see what comes of it.

Kash