How to remove/repair this shower drain

[Strategery]

I have a shower drain that I suspect to be leaking, but I’m having trouble figuring out how to remove it for replacement/repair. I do not see a castle nut or any slots that could be used to unscrew it from the base. Any assistance would be appreciated.

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• Strategery
• Dec 14, 2019

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• Strategery
• Dec 14, 2019

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• Strategery
• Dec 14, 2019

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• Strategery
• Dec 14, 2019

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• Strategery
• Dec 14, 2019

 

[breplum]

There is a big nut underneath that holds the drain in place (and sometimes/often they slip the threads or crack).
The preferred drain for showers is made of brass, which never crack or have problems.
The brass shower drain will have a castle nut.
No access from below: Call a good plumber.