Hi McLoffs I've seen lower ball joints partially "seized" on more than one 124 in the past few years. It's usually only one side. The result is that more force is needed to turn the steering knuckle on the side with the bad ball joint. I know you said it was looked at already, but a check for looseness won't discover the problem because it's not loose, it's tight. This will give the car a very strange feeling under a variety of driving conditions. With the car on a lift, LOOK very carefully at the lower ball joints. Any sign of rust (usually a brownish color on the dust boot ) and that's it. The lubricant inside the sealed boot is long gone, and the ball is just grinding itself away. The extra effort required to turn the knuckle isn't usually noticed by the driver because the power steering can easily overcome it. Don't spend a dime until you have this checked! Good luck