Single Handled Shower Faucet Removal Help

I am pulling apart a single handled shower faucet to get to the cartridge or gasket or whatever is allowing water to leak.
Where I am at:
I have removed the set screw on the handle and taken that off
The next piece has a center screw that I removed with a phillips screwdriver.
Now
Ive watched help videos and my faucet closely resembles the singled handled Moen with an internal cartridge.
However ......
The piece that I am having trouble with is not plastic. Looks like pewter or aluminum. Please see attached pictures
Ive tried pulling this piece straight off/out.
Should this just pull out or are there splines that you have to align?
If it is supposed to just pull off is there a lubricant that could assist me?

Thanks in advance

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Lets try this again

You will need a moen cartridge puller most likely

Posting pictures

Once you have removed the screw in the middle, they usually slide right off. However, I've fought with the old metal ones like that when they corrode to the stem of the cartridge. Grab some penetrating fluid, then don't be scared to give a strong tug. It will come off.

Like matt said. be careful not to break the stem. I have had a few where the stem separates from the plastic core. Then I have to get creative because with out the stem it becomes very difficult to remove the core.
Take a hacksaw and cut the handle adapter off, leaving part of the stem.
Then you can remove the chrome tube for access to the clip that holds the core in.
If the stem breaks I have used a 1/4" lag bolt. drill a 3/16" hole in plastic core and or heat the screw red hot screw it into the plastic. wait until it cools and plastic re-hardens. use the screw to pull it out.