In the following sentence:
In the sentence bold above, if I understand it correctly, the meaning is something like the follows:
The parts have been upgraded to more robust ones and to some extent optimized.
However, I don't understand the grammartical structure of the bold part. Specifically, what I don't understand are:
What does 零部件 (parts) modify via 的? Is there something omitted here? For me 更换 seems to be a verb so it is awkward that 零部件的 modify it.
以及 means "as well as", and works as a conjugate. But what does it concatenate here with what?
How does 上 work here?