AS, I spray(food grade silicone) on the threads of the auger body and ring also
I've got that grinder and have had no problems but I am going to take the cover off and try to grease it as a preventative measure.
I bought the Kitchener 15 lb stuffer and it has all metal gears. They have since discontinued my model which is a shame because it is a great stuffer and I got mine at a good price.
I originally bought a LEM and had problems with the threads on it. I returned it and was not pleased at all with their customer service. Even though the newer Kitchener models that I've seen have nylon gears, I'd still buy it over the LEM, just because of the problems I had with customer service.