Oster Golden A5 clippers not cutting

Question

I have the Oster Golden A5 clippers. I was clipping my chow mix and the just stopped cutting. Blades are moving but the hair is not cutting. I used the Oster Wash and they started cutting for just a bit, then they stopped cutting again. I used the wash again but they did not start cutting this time. I took the nameplate off and brushed away any hair. Still not cutting. Any ideas?
Thanks