easy, from the front push the bottom seat in or back then up to unhooked them from the floor, 2 locations (underneath from were one sits) then remove torx bolts holding seat
belt buckels & back seat, finally lift up back seat and pull out..
First you remove the lower back seat, and the bolts that secure the upper will be exposed. Remove them and lift out upper back seat.
Back seat has to come out and the rear package tray too and then you can get to the bolts that hold the speakers in.
lever along side drivers seat.
Use a 10mm socket.
It is under the car near the frame almost directly under the back seat on the drivers side. Very easy to replace.
get in your back seat. feel along the bottom edge of your seat. you will feel two bolts. remove these and the seat will come right out. just did this to my 91 cutty to see if i could get to the fuel pump from there. 6 696 6969 12 12 dont listen to him...he cant spell
Make sure wires are not disconnected Maybe bad switch maybe something restricting movement
Push on bottom of seat front side from floor towards trunk (takes some effort) until unit unclips from locks -- then lift out You may try to lift from back of lower seat cushion first and then slide to unclip, but I've had better luck the first way
You will probably end up having to replace the belt as I don't think there is a way to tighten it.
replace the seat belt
On my 1984 190E, it is simple - there are a couple of tabs at the bottom of the back seat (where your heels would be if you were sittng), you have to look, the seat will pull right out!
Look under your seats the rails for moving the seat back and forth there will be some bolts that go into the floor. Simply take out the bolts and make sure to unclip any wires so not to damage them, and this should do it.