Shifter Handle

Brewers offers a rebuild service. I think passon does as well. I could do it but it wouldnt be any cheaper than they are.
Yours has been sandblasted. I would at minimum take it apart for a cleaning. There is no way to get all of the old grease and sand out without disassembly. If you buy the kit it comes with detailed instructions. Its not difficult at all and requires no special tools. Take a bunch of pictures of the levers before taking it apart.