We saw pictures of scaffolding up around Buzzy in 2013, after he had been cleaned up/repainted. We've never had a clear answer as to what was being done to him, whether this was just his repainting or him being tested. His hands and fingers are in different positions in the scaffolding pics than pics of the next time we saw him, so it seems he was at least running a bit.
Also as I am inspecting these pics, I'm pretty sure the animatronic only has two fingers on his left hand, I guess because he doesn't use that hand during the show much beyond holding the lever so they didn't need a full articulated hand like his right is.

Just interesting.