This is a FAQ and if you do a search on odometer repair there are details galore. Basically the most frequent cause is a gear smaller than a dime in the speedo/odo that fails - the teeth basically strip off. A replacement gear costs $29 and there are pics and step by step instructions on how to R&R. As for breaking one of the 4 ears, lube the threads on the 4 black screws and don't overtighten anything plastic ever. You can R&R the cluster 100's of times. When removing the cluster, have a pad and pencil handy and note the position and color of each wire, note terminals not used as well. Don't drive the car w/out the cluster as the charging system circuit is broken and driving it will drain the battery.