Sorry Mike, I can’t answer your question because yours may be different than mine. My gears, all 4 of them, were 15 tooth but yours may be different. I can say that all my gears were the same, so if you can see one of them clearly enough to count, the other should be the same. The other option is, if you are stationary for awhile, is disassemble the mechanism, which you will eventually have to do, and determine which gear you need. I found my parts on Amazon and paid the small extra shipping charge to get them overnight. Good luck with your repair, it really isn’t a super difficult process. One word of advice, order at least one extra gear, I thankfully did, because, during the repair, I found the gear on the same slide was bad also. Wish I had order 3 now since I don’t have a spare.