As noted in the MLA Handbook, “When a source has no page numbers or any other kind of part number, no number should be given in a parenthetical citation. Do not count unnumbered paragraphs or other parts” (56).

The same principle should generally be applied when you cite sources that inconsistently supply page numbers: do not count pages to supply missing information. So if a work you are citing displays page numbers in some sections but not others, cite page numbers when they appear, and omit them when they do not. Then at first mention of the work in your paper, include a note explaining the inconsistency in the source.

Use judgment when applying this principle, however. If damage to an otherwise paginated manuscript caused a few scattered page numbers to be obfuscated, supply them. 

Work Cited

MLA Handbook. 8th ed., Modern Language Association of America, 2016.