Maybe wiring. If the woofers rub or have other problems, then you're screwed. The alum. diaphragms should be quite work hardened by now, so will probably have more limited BW than OEM or modern replacements, so as a collectible, you must keep them, but for everyday playback, store them and use GPA's.

Mostly my comment referred to the front end electronics, pre-amp, etc., which of course could mean anything from using as is if already competently rebuilt or need all new caps, resistors, tubes, etc.; basically everything but the chassis parts and iron.

GM