Learn French: Je venais solliciter votre assistance. - I was coming to request your assistance.

This is the imparfait d'atténuation (imperfect of politeness). Even though the action is happening in the present, using the imperfect softens the request. It makes it sound less direct and less demanding than saying Je viens (I am here / I have come). It is very similar to how English speakers say "I was wondering..." or "I was hoping..." to sound more polite.

How does the tone change if I just say Je viens solliciter votre assistance in the present tense?

Using the present tense is grammatically correct, but it sounds much more direct. By saying Je viens, you are stating a hard fact: "I am here to ask for your help." In professional or formal situations, the imperfect (Je venais) is preferred because it creates a polite distance, making the listener feel less pressured.

Why is there no preposition (like à or de) between venais and the infinitive solliciter?

Verbs of motion in French, such as venir (to come), aller (to go), descendre (to go down), and monter (to go up), connect directly to a following infinitive without any preposition. This rule applies regardless of whether the verb of motion is in the present, imperfect, or any other tense.

Solliciter translates to "to solicit" in English, which can sound quite strong or oddly formal. Is it normal to use this in French?