Here is a pdf of Dovid Katz’s Grammar of the Yiddish Language, still by far the most comprehensive and reliable grammar. It cointains detailed gudance on phonetcs, noun genders and plural formation, cases, verbal conjugations in all moods, periphrastic verbs, adjectives, syntax and semantics.
It is currently out of print:
J Mazin’s A manual and grammar of the Yiddish language (1927)
See also the Yiddish language learning bibliography here.