Is this slow leak easy to repair?
What is the torque for the 12mm bolt in the picture?

722.418 transmission.
1992 300D 2.5 turbo diesel, 288900 miles.

The right rear area transmission pan gasket was wet with red fluid. I wiped it off and also wiped off fluid above the gasket. Then I put a white paper towel above the area and turned on the engine, did P->R->N->D->N->R->P, and then turned off the engine. The white paper towel obtained fresh read dot, while the pan gasket did not become wet with red fluid.

So the ATF seems to leak at or from below the round shape part 123 277 0103 in the picture.

The right side of the picture is the car's front direction, up side of the picture is the sky direction.

The managed to put 7 inch ratchet into the tight space to tighten the bolt in front of the round shape part 123 277 0103. The bolt was not loose, but I could rotate about 60 degrees. I could rotate more of course with stronger force but I did not tighten further. The slow leak continues.

Attached Thumbnails

 

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.