Speedometer cable issue

I ended up buying the cable from Fowlie, and installed it after cleaning and lubricating. And it worked - up until 25 mph or so, when the speedometer needle started swinging wildly. It looks like I need to pull the speedometer and service it. It looks like this is something that can be done from the front of the dash - correct? Remove the four screws in the corner of the panel, and then remove from the panel itself?