Be very careful around that, as the tank is under pressure. I am sorry I don't have a filter like yours so I am of little help. I "googled" and see a lot of the Haywards have the multi-port on the top and pressure gauge on the side, and my one of a kind filter is not like that. My multi-port joins by union on the side and my lid is anchored on by screws and my pressure gauge is on that lid.
Just be careful around it and make sure it doesn't "blow" its stack and I would think if that cracks up on the inside if pressure holds it could put sand into the pool. Not certain on that. Hopefully someone with you type of filter will see this and let you know the best way to fix that.
As far as the deep cleaning went, was your sand dirty/ channeled? And how did your laterals look? I actually deep cleaned mine a couple times before I decided to change the sand, there was sludge in there ~ my back yard is all birch tress and I swear they are the worst kind of tree to have around a pool. My sand hardened, the black bud off the birch trees solidified to a sludge.
Hopefully yours cleaned up well. As far as my laterals went they were all in one piece, I saw nothing broken so I assumed they were ok. Were you able to get yours out to inspect them? Just curious what you results were upon tear-down.
Best of luck with everything ~ I hope the filter functions as it should and your water clears.
