You are right about the pipes collapsing, but the chance of that is VERY slim, unless the car is being used in the desert or in iceland, I reckon that the bearing that only goes half a rotation is no good, thing is that Lexus bearings are not cheap, £60 ish from memory for a blue print bearing, then garage labour to fit them on top of that. I had both front bearings on mine changed a few years ago which made no difference to discs warping and causing the wobble under braking, infact the bearings collapsed again a year later! The garage had obviously not put them in right, although they wouldn't admit it. Do yourself a big favour and get on ebay and buy second hand original Lexus hub assembly which has original bearing for maybe £30-40. With a bit of luck this will probably cure the warping disc saga as well, the same as it did for me!!