Rebuilt A 833 front oil leak

I am experiencing the same thing as I8NEMO did, but different problem. I have a used 833 bought from a person who said he rebuilt it. When I got it home I noticed it had cracks around the bearing retainer casting bolts (from over torqueing I assume). Ordered a new bearing retainer and seal/gasket kit from Brewers. I could have easily replaced the retainer myself, but decided to have a pro look it over, and replace seals and gaskets, so I took to a local trans shop for an inspection, reseal, and bearing retainer replacement. Got it back and they said it looked good inside and I was good to go.

I have the engine and trans on a built up box on casters, as I have a lift and will be installing the assembly from below. I put Pennzoil Synchromesh oil in. About a week later I noticed fluid leaking, and it was coming from the front of the trans. Removed the trans from the engine and found the plug at the idler shaft to be the leak point. I'm hoping I can fix this without having to bring it back to the shop. How do you remove and replace the plug? You can't see the oil because it got wiped off, but it definitely is leaking.

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