How do you get the dip stick out on the transmission,,looks like avg dip stick

there is a dip stick and i dont mean the one for the oil it is on the pass side of motor toward the rear,,just where a tranny dip stick should be..but it wont pull out..

Its only a plug there is no stick on other side of cap that tube is for filling fluid. Mercedes may sell a dipstick but they refer to itas a tool im quite sure

ok thanks..