The veg tends to stick the vanes in the rotor if they are left standing. The one I had used a very thin cellophane type gasket to seal the cover, this ripped the first time I stripped it down so I made a new one from a cereal packet. It then decided it didn't want to work anymore, I realized that a close fit between the rotor and the cover was important to create suction, something I removed by using a thicker gasket. Some thin gasket paper sorted it.
I don't use one anymore but I used to play a hot air gun over it whilst frantically wanking the handle if it became gummed up from storage.