With the speaker disconnected, gently move both woofers. See if the "good" and "bad" woofer move with the same degree of freedom. If the bad one feels in any way different, then that’s your answer. Make sure your amplifier is off for this, as amps with negative feedback will resist cone motion.
They should move easily, like pushing into a Krispy Kreme donut. :)
They should move easily, like pushing into a Krispy Kreme donut. :)