fly in the ointment vs jigsaw

fly in the ointment

noun
  • Something (especially a minor thing) which ruins or spoils everything else, or makes it less pleasant; a nuisance or problem; a disagreeable or unpleasant detail. 

jigsaw

noun
  • Something that can be compared to a jigsaw puzzle. 

  • A power saw with fine teeth and a narrow blade which can cut curves in wood or metal. 

  • A jigsaw puzzle. 

verb
  • To cut something using a jigsaw. 

How often have the words fly in the ointment and jigsaw occurred in a corpus of books? (source: Google Ngram Viewer )