The little plastic gears in the back broke. Happens all the time. There is a straight gear and a worm gear. Takes a little bit of finesse to get them in, but it's not complicated. If you are not inclined to do it yourself, just about any mechanic can do it. You might want to try taking the cluster out yourself. The toughest part of that is getting the headlight switch knob off. Sometimes it pops right off, sometimes it's a bear. If you got that far, the tough part is over. The rest of it is no harder than fixing a child's plastic toy. The bezel pops off, there are 4 torx screws holding the cluster in, and two big electrical plugs on the top back. While you have it out unplug the big electrical plug on your headlight switch. 9 times out of 10 it will have a big melted spot in the middle of it. Ford used that same basic headlight switch for 40 years, and they all melted at some point or another.
The cluster comes apart real easy too. There is a series of torx screws holding the clear plastic cover on. Once you have that out, the gauges pop out in 3 parts. In the dead center of the backside you will see two little white plastic gears missing some teeth or cracked.
Kurt