In some cases you may need to change the strut, upper strut mount or the spring, for this the strut assembly has to be brought out of the vehicle. First of all, Fix a spring compressor on the vertical shoulder of the shop vise and put the coil spring on the spring holders, observing that three coils has to be between the holders before pressing the spring. Unfasten the strut nut using a 'puller,' and hold the strut shaft with a 6 mm Allen wrench at the same time. I have found it rather crucial not to employ an impact tool during this process. After taking out the upper strut bearing and its related parts, if a new coil spring is being fitted then, release the tension of the spring compressor and take out the coil spring. Inspect the strut dust boot, rubber stop and spring pads and replace these where required. In regards to replacement parts, springs should always be replaced symmetrically and there is BMW ID number at the end of the part. Disassembly is done in the reverse order of assembly whereby a new upper strut self-locking nut will be tightened fully, then release the spring compressor. Do not use and impact tool on the strut nut when trying to tighten it. Check and accurately fit the upper and lower spring pads onto the spring seats and with equal and slow steps, release the spring compressor on the spring. Last of all, get the vehicle aligned by a professional after the job has been done.