I recently bought a HEXTRONIC HXT900 mini servo and have just found out it barely turns. For this reason I thoguht it might be because there is no grease visible. My question then is: Any grease will do?
Can't help you on the grease, I'm afraid, but just to say I recently bought four of these and three of them are the same as that :(
Not all grease is good. I would not recommend silicone here. If you can use lithium, it's the best for this application.