Steering Wheel Shimmy Advice Needed

Had my tires rebalanced at a tire dealer a couple of weeks ago. They said the front right wheel had a slight bend - knew about it and its been like that for ages.

Took the car to the dealer who uses a contractor to straighten the wheel. They did a road force balance at the same time. On the highway the shimmy is still there at around 60 mph and you see the empty passenger seat back vibrating. You don't feel anything in the seat but you do feel it in the wheel and see it slightly moving. If I move the wheel quickly back and forth - even if its not vibrating I can feel something isn't right at speeds but it will correct itself after a second or two.

Took it back this morning and had them check out the suspension. Service advisor said the front suspension was tight but the back shocks appear to be leaking. Would they cause the steering to vibrate? They said they would call my aftermarket warranty to get approval which they won't because they don't cover shocks and I would never have them do it because of the cost and its something I can do in about 1 1/2 hours. If the dealer fudges it and says its something else fine.


Does any of this make sense or am I being led down a costly road? The car even with the bent rim when the tires were mounted last year in October never did this. I got them balanced because of the slight shimmy but the balancing didn't improve the situation so it must be suspension based. What should they have checked?