Dude, I've only messed around with my SC once so i don't have a lot of experience but based on those two videos, everything seems normal. Unsure why you need shims when there is one visible (possibly 2 stacked) sitting on your SC in the first video. Im also struggling to understand how the shaft could be warped or worn. Is it a high mileage car? You may want to consider getting a second opinion from another mechanic. Hope you get your car back on the road soon. Good luck.