”Vilja” is the infinitive form of ”vill”, so you do have it there.

• Hon vill simma. (She wants to swim.)
• Hon brukar vilja simma. (She tends to want to swim.)

Because in the English sentence "She usually wants to swim …" (Hon brukar vilja simma), rather than "She wants to get in the habit of swimming …" (Hon vill bruka simma).

Also, bruka is a verb.

(att) vilja = (to) want (to)

(att) vilja att … = (to) want (that) …

in the first form, "vilja" acts as an auxiliary verb and requires another infinitive main verb (unless you are a toddler). the "to" of "want to" is automatically implied and has no separate swedish translation. you simply append the main verb in the infinite form (here: "(att) vilja simma", "(to) want to swim").

in the second form ("(att) vilja att …"), "vilja" acts as the main verb and the trailing "att …" introduces a subordinate clause that requires another subject and verb, but that was not duo's question and you missed to provide a subject for the subclause as well. "hon brukar vilja att simma" literally translates to "she usually wants that swim(ming)", which makes no sense.

"(att) bruka" is yet another auxiliary verb that requires an infinitive verb to follow (here: "(att) bruka vilja …", "(to) tend to wanting (to) …" or "(to) be used to wanting (to) …" or simply "(to) usually want (to) …"). because "(att) bruka" is the first verb in this train of verbs (i.e. in the predicate of the sentence, "(att) bruka vilja simma") it gets conjugated to "brukar".