How is this bathtub overflow drain supposed to be assembled?

Factual Questions
1

My bathtub overflow drain leaks like crazy and it rains downstairs. When I take the cover plate off here is what I see:

[Album] Drain

There are a few problems here. There is nothing to keep the drain assembly centered in the tub enclosure hole – there’s a gap visible from 7 o’clock to 9 o’clock that connects the tub interior to the wall cavity behind the tub. And the gasket is quite hard while the tub enclosure flexes really easily, so the gasket doesn’t deform at all.

Most mysterious are the metal tabs, which fit between the gasket and the back face of the tub enclosure, which prevents the gasket from coming into contact with the tub enclosure. What is their purpose? Maybe they’re supposed to keep the gasket from falling off during enclosure installation, and the installer was supposed to pull them out after the enclosure was in place? Or maybe they are supposed to pull them out a little bit so they were on the visible surface of the enclosure rather than between it and the gasket?

I don’t have any of the information about the enclosure or drain, such as manufacturer or instructions. It was done professionally.

Any insight would be greatly appreciated.

2

I am not a plumber! (I wear suspenders)

I am not able to see what you are describing other than the tabs and what looks to be off center.
1st of all, an overflow drain is also a drain breather.
That being said, if you were to seal the drain you would probable see issues with the tub draining.
But, the drain is for preventing an overflowing tub.

You are going to be in for an expensive replacement/repair on this!

Good Luck!

3

My WAG:
The tabs are supposed to be in FRONT of the tub surface. They keep the overflow centered in the hole (which is why it is leaking right now). They are there just as an assembly aid.
The screws on the cover plate snug the gasket tight against the back side of the tub to prevent leaks.

4

How often do you over fill your bath tub?

The metal tabs should be on the inside of the tub.

5

Yep. The tabs should be on the inside to keep it stabilized and centered and there should probably be a ring of plumbers putty between the tub wall and the overflow pipe if the black part isn’t some sort of adhesive sealant. Otherwise just center the pipe and make sure the black ring is sealed tightly against the tub. It may help to heat the tub wall with a hair drier to get the best seal.

Note: Do not use the hair drier in in the tub while water is in the tub.

6

I know. The heat would make the water expand and overflow. Snnipe 70E was asking about that.

Snnipe, in answer to your question: once.

7

I wouldn’t hire them again.