Mercedes: 83 380 sel trans problem and floor button, vacuum servo, vacuum leak

Question
QUESTION: hi. 2 questions. first, wondering what the floor button is for that is under my gas pedal?
second and more important, ive owned my 83 380 sel for a year now and runs great, but every once in a while as i start off, trans does not go into 2nd gear.. i solve it by stopping, putting in park, and restarting and all is fine.
i assume this is a less complicated manual transmission than modern ones and hoping its just an adjustment. look forward to your response...sal in new york

ANSWER: Sal,
Is the button functional? or just a stop for the gas pedal? Is it in direct alignment with the pedal or just to the side?
Regarding your second gear issue.  I am un clear as to if the transmission is automatic or requires a clutch. If it is a manual shift, then I expect that the synchronizes may be worn and not allowing the fork to engage the second gear. When you stop you are able to realign the teeth to make it shift.
If it is automatic, you may have an issues with the vacuum servo to up shift to second.
How often does it hang. How many miles on the transmission? Has the transmission been serviced with new fluid and adjusted in accordance with the Mercedes service schedule?
Let me know OK?

---------- FOLLOW-UP ----------

QUESTION: button is right under gas pedal but cant tell u if its functional because when i hit it i dont notice any function taking place...and its an auto trans...when it happens, it won't go in second at all, until i stop car and restart. 175k on tranny. no knowledge of adjustments or new fluid. thanks

Answer
Time to take the vehicle to an independent Mercedes transmission shop. It is clear to me that this cannot go unattended. If you have a vacuum leak then it may a simple fix. A Trans... Mechanic can offer a better idea about the least expensive way to to solve the problem.
Does the transmission have any fluid leaks?
Good Luck
Rob