She has seen the letter. She has a letter. The same word, the same spelling, and two different jobs. In the first, has is a helping verb: it stands in front of seen and carries the tense. In the second it is the verb, and it means that she holds the letter.
The word after it decides which. If a participle follows — seen, been, written — have is a helping verb. If a noun phrase follows — a letter, no pleasure, much to say — it is the main verb.
The lab sorts all 37
Chapter XXVI has 37 forms of have: have, has, had and having. The lab steps over not and short adverb words and reads the next word. It finds 17 helping verbs, which is 45.9%, and 10 main verbs. Zero are have to. Three are filed as questions, because a pronoun follows have, and seven as something else.
The seven the scan missed
Look at the three: she might have foreseen, the event has proved you right, apparent partiality had subsided. Each has a participle after the helping verb. The scan's word list does not have foreseen, proved or subsided as participle forms, so it could not place them. Now read the other rows. Four more are helping verbs too. Had by some accident been lost and if he had at all cared have a phrase between have and its participle, and the scan files them as something else. Had fortune permitted it and for had I really experienced are the old way of saying if, with the subject moved in behind had; the scan files the first as the main verb and the second as a question. Add the seven and the split is 24 helping verbs against 13 others, 64.9%. The number the page prints is the scan's, and the rows tell you the rest.
A small count and a large one
37 forms is a small count. Counted once over the whole novel and quoted here, have appears 2,339 times, and 59.5% of them are helping verbs, 32.1% main verbs and 1.1% have to. The page's lower share for the chapter is the scan's reading, not the chapter's: by hand the chapter gives 64.9%, and the novel's count comes from the same one-word scan, with 6.8% filed as something else. In the play The Importance of Being Earnest, quoted the same way, the split is 50.1% helping verbs, 42.0% main verbs and 2.9% have to. In the two modern documents the lab counts 16 helping verbs in 23 forms, 69.6%, 3 main verbs, one have to, had to do, and three filed as something else, had violated, has diminished, has morphed, all helping verbs with a participle the list lacks.
Two phrases the scan reads as their parts
We had better not mention it. The scan reads better as no word it knows, so it files had as something else. The phrase had better is one unit, and it gives advice. I would have you be on your guard is a third use of the word: have with a person and a bare verb after it means make or let, and the scan, which sees a pronoun after have, files it as a question. Rows like these are in the lab's counts, and they are the reason to read the rows.