1987 260E W124 model.

I pulled up the rear seat at the back of the car, so I can have a look at the vacuum pump & convenient module, because I plan to hook up a keyless module (so I can open the car door with the remote keyless control). Anyway, I pulled the two red tabs on each side of the seat bottom, and the seat was pulled up effortlessly. However I can't seem to
be able to position the padded seat back in place so that I will lock to the
two red tabs again. I just wanted to take a look at the wirings. How can this seat be put back? Thanks in advance.

It should be a piece of cake if lined up properly. The little red things go into holes in the bottom of the seat. You need to reach under the seat to make sure the holes are lined up before you push down. If you pushed down with any force lacking proper alignment you may have crushed the little red clips (voice of experience), and they would then look like red pancakes rather than red teepees, in which case you'll have to replace them at a cost of only a few dollars at any dealer.