Have you taken it apart to ensure the seals aren't merely unseated?
If not, the seals may be ok, just fit them correctly and apply silicone grease where the seals move against the other parts of the headset.
As you mentioned the spring in the derailleur, do you mean shifting to smaller cogs? That's upshifting to higher gears.
It may be time to replace the cable and housing.
Even a new hanger may need to be aligned to the frame.
When Bosch made TOUR+ available in 2022, I had my bike shop add it. It goes in the place between ECO and EMTB ('21 Trek Rail 7). It provides boost levels from ECO to TURBO, depending on rider input.
I rarely use the other modes now.