If the worm gear referenced in the DIY is loose, the shaft will move out from the gears it's supposed to drive and your odo will be non-op. The basic problem is that the gray number wheel on the end of the axle is supposed to be tight to the little axle. If it's not, it will slip and not drive any of the odo number wheels. You can, with patience, slide out the axle just enough to give it a "nice" tap with ball pein hammer, the object being to deform the axle just enough so that when you push the gear back into place, it binds on the shaft.
I've done it a couple times in 2002s and my CS speedo. You can also, if you have more patience, reset all the number wheels to zero. If done for the purposes of defrauding a customer in a sale, this is of course illegal and most states have laws stating what you can and cannot do to an odometer. I bought my CS with a non-op odometer and left it alone for over 15 or so years, before I got the gumption to remove the speedo, fix the clock (a whole 'nother story) clean the speedo and clock faces, and blip the odo shaft so it works.
It isn't "a" rainy day project, best you allot several days so your immediate level of patience isn't exceeded. But OTOH it's "one of those things" that most coupe owners will do at one point or another. Some use checkbooks to make it happen, but professionals for this sort of thing need to be state licensed (at least here in Hawaii).