My old B7 A4 went, the first signs were viabrations when getting close too and on full lock, my b6 started to do the same not to long ago, however the issue of the viabrations is caused by the pulley on the alternator which has a bearing and a slipper clutch arrangement to
help smooth out viations in the belt speed due to sudden increased electral load, and the general pulsing of a diesel on tick over seizing, this then causes the power steering pump to pulse when under a lot of load around full lock which can damage the rack seal, so if your alternator belt is juddering more at idle and the tensioner is jumping around abit look at getting the alternator pulley changed, the parts £50 and its at most a hours labor to whip the alternator off, use a puller to take the pulley off and then rebuild it, my indi I use for jobs I cba to do like clutch changes etc charged me £100 all in inc vat, since then touch wood it's been fine, I also try and keep off full lock if I can too to reduce stress on the rack,
And 3 years ago a new rack was £550 on trade! And you could only get OE racks