Learn Turkish: Onu cilalamamıza rağmen, usta parçayı henüz monte etmemiş olacak. - Despite us polishing it, the mechanic will not have installed the part yet.

The main verb monte etmek (to install/assemble) takes the negative suffix -me and the perfect suffix -miş, giving us monte etmemiş (has not installed). Then we add the future auxiliary olacak (will be). Together, they mean "will not have installed." Notice that the negative suffix goes on the main verb, not on olacak (so it is not monte etmiş olmayacak).

Can you break down the suffixes in cilalamamıza ("us polishing")?

Sure! The root is cilalamak (to polish). We drop the -mak and add the verbal noun suffix -ma (polishing). Then comes the first-person plural possessive -mız (our). Finally, we add the dative suffix -a (to). Literally, it translates to "to our polishing."

Why does cilalamamıza need that dative suffix -a at the end?

It's required by the postposition rağmen (despite). In Turkish, rağmen always follows a word in the dative case. So to say "despite [something]," you must build the phrase as "[something]-e/-a rağmen".

Does henüz always mean "yet" in negative sentences like this?

Yes! When used with negative verbs like etmemiş olacak, henüz translates to "yet." If the verb were positive, it would mean "just" or "recently." It fits perfectly with the future perfect aspect here to emphasize that the action still won't be completed by that future time.