722.6 leak at rear

1998 ML320 53K (post harmonic balancer failure, unrelated) drops one or two drops of tranny fluid on the driveway every day starting about a month ago (bitterly cold NE weather). Fluid appears to be weeping from around the parking lock cable at the rear of the tranny on the drivers side. Checked the fluid level with the MB tool (also checked temp with a flexible thermocouple probe) and it’s still right on the money although not even close to red. Is this a common thing with these “sealed” units? Does the leak get worse? If I was to DIY a fluid/filter change, how difficult is it to replace whatever seals are on the parking lock cable? Does anyone have a diagram of what’s involved? I’m thinking of fashioning a diaper for the tranny, but fixing the leak would be preferable if needed.