You shouldn't have loosened the NSS bolts because now you have to recalibrate it. The bell crank into which the shift rod attaches is held by a nut and bolt on the pivot axis of the bell crank. I believe nut and bolt take 8mm wrenches. Remove the bolt, don't just loosen, then slide off the bell crank. Note through which hole the shift rod attaches so you press the bushing into the same hole. I press the bushing at ambient temperature with lots of SilGlyde, appropriately sized sockets and big pliers. Others put the bushing in boiling water to soften it, still others use a special tool made for pressing in bushings. There's a dozen other ways.

The way I calibrate the NSS is to turn the key to on with engine off and transmission in reverse. Have some inform you when the reverse lights are on as you slowly twist the NSS through its adjustment range. Find the center of the range that the reverse lights are on then tighten the bolts.

Reattach the bell crank making sure the plastic lever and pin properly engage the bell crank. Otherwise you'll need a new NSS.

Sixto
83 300SD
98 E320 wagon