Can the crossovers on my loudspeakers be rebuilt?

They are BIC America Formula 2's from about 1973 or so Impedance 6 Ohm I have them hooked up to a Kenwood Stereo Receiver from 1999 and the tweeters do not output any sound. Are they repairable? Woofers are in great shape and sound nice no dry rot with the rubber surrounds.