T56 shifter leaking.

[Sieg]

That appears to be seeping not leaking I wouldn't worry much about it. The pivot ball needs a some lubrication.

The way to fix it is design an internal seal or baffle to shield the underside from the oil blender.

Make sure your vent line isn't pinched and the check valve is functioning, it should limit pressure build up to roughly 5-10 psi.