I replaced the drive shaft and flex discs on my w123. If the flex discs are bolted tightly and the big nut on the drive shaft is as tight as it will go. Should the flex discs be flat or is it OK for them to be slightly stretched and bent out of shape? I loosened the mounting bolts on the center bearing support to equalize the tension and it seems the only way to flatten the discs is to loosen the big nut on the drive shaft. That doesn't seem to be a good idea. Any advice? Thanks.