When having multiple figures of the same device from different point of view (from left side, front side etc.), should we use the same numbers for the same parts, or number them again? And should we describe them again when describing new image?
You need to use the same number for the same part in all drawings that show and number that part. Furthermore, the parts should be named.
All springs, for example, would not have the same number. Different springs probably have different characteristics and roles so they would get different numbers. In addressing each figure you might say, "FIG. 2 shows an exploded view of the apparatus of FIG. 1 and shows more clearly that the main spring 10 is connected to the left peg 11."