I was wondering about the mechanics of a phrase such as "He didn't know how it worked". I place my curiosity on the last word: "worked"; more specifically, I am wondering if there is a strict rule regarding whether it should be "worked" or "works" based on intention. I often see the past tense used in such a case ("how it worked", then), even if the object in question still applies to such things. To make my question more concrete, shouldn't it be "He didn't know how it worked" in the case that the properties of the past no longer apply to the state of the object currently, and "He didn't know how it works" in the case that said properties still apply at the time of writing? This would add more freedom of clarity, as "worked" implies the object no longer works in the same way as it used to when "he didn't know" how it did work. Would "works", in contrast, imply that the way the object works has not changed?
To quote, Mitch Hedberg: "I used to do drugs. I still do, but I used to, too."
In English we can express a state in the past without reference to how it might currently be. When we say, "He didn't know how it worked" we mean that worked was at the time (or leading up to the time) of know. This doesn't directly indicate how things are now, either the knowing or the working. Without context, this is the preterite. He did not know how it did work at that particular time in the past. But to say something worked in the past doesn't mean it does not also work now or at any other point in time.
On the other hand, if we say, "He didn't know how it works," we are talking about the status of works being ongoing to this point. He didn't know at a certain point in the past how it worked and continues to work.
Additionally, we can say, "He doesn't know how it worked," meaning he doesn't currently know how something worked at some time in the past.