speedometer drive gear chewed up.
 

Hey all, so I have a 89 22re 4x4 pickup. I have been experiencing trouble with my speedometer drive gear. I have replaced it once and my speedo jumped to life for a full day. At first it didn't read the correct mph, then it suddenly died again. Pulled it again this morning and the gear is worn in the center, and a little chewed up. WHAT GIVES? I got the gear from the factory, my speedo cable turns at both ends, and I'm left scratching my head.