I have another guy that contacted me about his MS120 and it just stopped rotating while using it. He took it apart and the drive gear teeth are gone. Contacted Cat and they discontinued this part new. Yikes! Anyone got one laying around.
Try these guys. http://contractorsparts.com/index.html
This store. HOUSTON 5606 Jensen Dr. Houston, Texas 77026 Phone: (713) 695-7162 Fax: (713) 695-7810 1-888-593-0554
Thanks for the information. I'll give them a call for sure.