I just had this exact problem. What fixed mine was that I had to disassemble the elevator and clean and lube the elevator slides and elevator arm pivot joints. On mine, I also found the elevator mounting bracket was slightly bent. I had to tweak it straight again. I also resoldered the connections on the elevator motor. After doing all that my elevator moves very smooth and is whisper quiet. Hope this helps.

I used a thin yellow grease that we use to lube electric motor splines where I work. I am unsure of the exact type of grease but it may be moly based.

I did see that Permatex makes small tubes of white lithium grease that should be good for the slides and pivot bushings on the elevator. Maybe someone else on here may be able to chime in on a good grease to use, but I would say a thinner grease would be best.