Coils freezing causing fan to stick and then make noise, whats root cause?

[guht]

Model Number: PFSS6PKXGSS
Brand: GE
Age: 6-10 years

In September 2019 my fridge started making a loud noise, which when I pulled it apart, I discovered it was due to the coils freezing over so much that it eventually froze around the fan which started knocking due to being froze.

The pictures are from September 2019 when the problem originally happened.

I defrosted everything manually, it made it 8 months, now it is making the same noise, and I can see through the slats that there is ice behind the panels like before.

So the question is:

• What are the most likely root causes?
• What part(s) do I need?
• Do the parts need to be professionally installed because of refrigerant lines, etc?

Thanks for your help!