Attention! There are two hidden dismantling holes on the end surface of the primary shaft seal.
Prepare the equipment "23.0.490", "23.2.380" and "23.2.340". Screw in the "23.0.490" tool (arrow, Fig. 8.13) into one of the two dismantling holes and remove (knock out) the oil seal from the manual transmission housing.
Lubricate the working edges of the seal with transmission oil. Install the "23.2.380" device on the splines of the primary shaft (1, Fig. 8.14). Place the oil seal on the primary shaft, moving it along the "23.2.380" device to the manual transmission housing and remove the "23.2.380" device from the primary shaft.
Using the device "23.2.340" (arrow, Fig. 8.15), press the seal (1) in until it stops. When pressing in, use a mallet or a hammer with a plastic striker.
Upon completion of the work, change the oil in the manual transmission.
Information taken from this resource: BMWman.ru