I can't even imagine how you'd get the parts, and they probably can't change the plans either. Ok so I decided to look into it a bit more, and here are some interesting details from documents on the nrc.gov and EIA.gov:
Here's some context for what was happening in 1985, from the eia:
>"As a consequence of the identification of a large number of deficiencies shortly before the WBN Unit 1 license was expected to be issued, the Nuclear Regulatory Commission (NRC) sent a letter to TVA [...]. In response to this letter, TVA developed a Nuclear Performance Plan (NPP) to address corporate and site-specific issues, establishing programs to address a wide variety of material, design, and programmatic deficiencies. WBN Unit 2 construction was suspended at about that time, with major structures in place and equipment such as reactor coolant system piping installed."
And while most of the documentation was very terse and spoke more about specific regulatory requirements that I don't understand, this is pretty interesting:
(From the nrc.gov)
>"The NRC staff reviewed TVA’s refurbishment program and found the following: (1) TVA was refurbishing or replacing most active components and instruments; (2) TVA had determined the potential degradation mechanism for each category of components, along with any contributing environmental factors; (3) the acceptance criteria were developed from the licensing basis, design specifications, and vendor specifications; (4) the proposed inspections and testing included in the program could be expected to identify degradation; and (5) refurbishment activities would be in accordance with applicable vendor and design specifications or requirements."
That sounds like a massive, massive amount of work. It explains why it took longer even if the reactor was apparently 60% completed.
(From the eia) :
>"That time, a study found Unit 2 to be effectively 60% complete with $1.7 billion invested. The study said the plant could be finished in five years at an additional cost of $2.5 billion"