How to repair a Mustee shower pan drain leak?

[Dave from OH]

I have a 20+ year old shower pan with a built-in drain from Mustee. The pan is fine but the drain has begun to leak. I expected that the drain could be unscrewed and replaced but that is not the case. See attached photos. The photo from below shows no nut that can be unscrewed. The photo from above shows what appears to be a rubber washer that is squeezed between the drain pipe and the drain assembly. I haven't yet attempted to remove that washer because I'm not sure that's the problem. It could be leaking between the drain housing and the pan, but I can't figure out how to access this. Any ideas would be helpful.

 

[PlumbNuts]

Can you tell where exactly on the drain the leak is coming from?
You might only need to remove and replace the rubber gasket that forms the seal between the drain body and the pipe.
Might even be as simple as tightening that seal.

 

[Sponsor]

 

[Terry]

I would contact Mustee for a new rubber donut seal.
The metal flange is installed at the factory, I've never had to replace one. I have done the replacement rubber donut though.
I believe that one time I smeared a little Silicone on it too while installing.

 

[Sylvan]

I used to remove the rubber donut and do a poured joint ...Lead oakum

 

[Sylvan]

I used to remove the rubber donut and do a poured joint ...Lead oakum

Thank you .. I had to do an hourly rate motel and installed 50+ shower pans they did not want to go for lead pans or Terrazzo so they supplied the shower pans and I installed them

 

[PlumbNuts]

I used to remove the rubber donut and do a poured joint ...Lead oakum

Lead and oakum on cellular core ABS?

 

[Sylvan]

I always use cast iron waste and vent and type L copper above ground and K copper tubing below ground