You can put a 3/8 sprocket on them. I did that with my 026, and promptly found a problem with it. I need to tear into it, and see if I can find the problem. Hoping it's the clutch. I should have thought about that in the first place, but not sure if I did. I got disgusted with the whole thing and packed it away. Got the clutch idea from the here with the video of a guy and his new Chinese saw. If not the clutch, time to take the p&c off, and see if it's good. Next best thing is new rings. Otherwise, it's shelve it til a donor saw comes cheap or free to get it going again.