Unless you have access to a very high quality clean room environment and a very expensive set of tools, you cannot service the inside of your hard drive. The platters are spinning at at least 5,400rpm, and more likely 7,200rpm, and the heads are floating above the platters are a distance much less than the width of a human hair.
You CANNOT service the inside of your hard drive without extremely specialized equipment.
Well, strictly speaking, you can, but you're not going to be successful, and then you'd have two ruined drives and no way to recover any data.
What you SHOULD do is make sure your important data is backed up, purchase a new drive and use it. Then take your old drive apart and marvel at all the shiny parts, because they really are quite pretty inside.
UPDATE
I don't normally watch videos linked here, but re-reading your question made me do so, and...
You've already ruined your drive.
The air pressure and humidity inside the drive is carefully regulated to provide the correct operating environment allowing the heads to skim so close to the platters without touching.
By opening your drive you ruined this.
By running your drive while it was open you exacerbated the damage.
It's cool to watch, but your drive is entirely and completely dead now. Not dead in the sense that the motor(s) won't run, but dead in the sense that any data that might have been there which relied on the careful arrangement of hardware and environment is now destroyed.
Dust particles are much larger than the gap between the head and the platter, and they are now gouging holes in the silvery material your data is written on that covers the platters, they are damaging the sensitive head as the platter spins beneath it.
Minute air currents are changing the tensions on your head and platters and pushing these together and apart.
So, forget the part about your data being backed up, and take this as a lesson: Don't open your own hard drive until you've written it off 100%.