I have just bought my SLK32 a cuple of weeks ago and noticed - not so much a Neutral event - but it isnt exactly smooth from 1-2.
It as also leaking from the connector.
I have a pan kit and connector ready to go next week for a change.

Anyway
Checked the fluid last night, "black locking tab" - indicating either was original (80k miles) or MB/dealer has serviced it - dont think so.
I used a 30" piece of curtain wire and pushed it down through the twists. Hit the bottom, pulled it out.My temp was 50deg from a laser thermometer on the pan. Level came up at 50mm - just about right (see picture), but will do a more precise check in the AM.
I was hoping it was lower - hence explaining the slip/catchup clunk I'm noticing, but alas....may just come down to the 10year old oil and connector leak just droping that little bit

Then again there are a few other issues with these trannys - one step at a time.