You could add some plastic in between the leaves to help them slide better, look at Terriann's website for details.
I strongly recommend going to a spring shop and getting an extra leaf for them. One of the biggest errors with these trailers is bulk vs gross. They are rated at 1500lb but given the size, most folks overgross them (as have I). They will handle it but you must be very gentle with it. Adding an extra leaf will provide some more margin for safety/damage.
I separated the leafs, wire brushed, painted, and reassembled. I asked a local spring shop whether I should re-grease the leaves before assembly and they recommended I not. They said it just attracts dirt and wears harder that way.