If it is the newer type, and has not seen years of heavy use, the problem is usually old dried out grease and dirt and can usually be repaired by taking it apart and clean and lube it.
They are very simple and very easy to take apart.
I cut the end off of a old screwdriver and made a slot in it to remove the screws, but they can be removed with pliers also.
Order new gaskets then take it apart.
Pop the front cover off then remove all the parts that are under the cover.
Next remove the top and the paddle.
Use solvent to remove all the old grease and dirt.
Coat the inside and paddle with grease, I usually add one or two drops of light oil to the grease to thin it, this makes it run faster.
Install the paddle and new gasket if needed and the top.
Install the parts under the front cover and put some light oil on everything that moves.
If the seal on the paddle is not torn or damaged, it should run good after it is cleaned and lubed.
I test them on the bench using a vacuum pump that is made for heat and air repair.
If the paddle is bad, you might want to send it to a re builder.
The parts to rebuild the paddle in the kits sold by the vendors are of marginal quality and very difficult to install and make work correctly.
