Replacing laptop fan and thermal paste

[Reggod]

My Lenovo Thinkpad T420s recently started displaying a Fan Error message at boot, and upon research, it appears that I'll have to replace the fan and heatsink. This is not a problem since its cheap to buy, but could someone point me to a clear instructable? Will I have to apply thermal paste as well?

 

[CountMike]

https://thinkpads.com/support/hmm/hmm_pdf/t420s_t420si_hmm_en_0a60241_06.pdf