OK, then not to be too technical, recognize the difference between WHEN there is a loss of speaker action, it is likely the crossover had a part come off, and having the crossover fall apart being common. Those are different things.
If I have a woofer but no tweeter, yes I will look at that Xover first, mainly because there is only one amplifier within, so if any driver works, then the amp works. I would say that my repair experience has been replacing blown op amp ICs more than fixing Xovers, one of the TL074s.
If you feel like spinning out the screws to pull the woofer and look at the crossover, well it isn't a big job, go ahead. If the cable tie wraps are broken, replace them with as heavy as will fit. You can pull it and check the back for cracked solder. I always thought that square in the center of the rear panel was not the least vibratory position. Up to me I might have put it near an edge of the cabinet.
If it works it works. the outputs are a couple of LM3886, which are reliable and sturdy enough. If controls are noisy, clean them, if a jack is intermittent, try some cleaner. I might push headphones plug in and out of its jack a few times to verify the speaker reliably returns when the jack is empty.