Looks like the 4 button switch, which as far as I can find is not available new and pickings are real thin used/NOS which by thin means I can't find them either. I did read somewhere that someone modded a 5 switch unit to work but other than that I know nothing about the mod. Looks like you might need to contact a rebuilder, show them your pictures and see if they can help. Hopefully they have patterns to make new sliders and the bits and pieces needed to replace what's missing. Who knows, maybe they cannibalize a 5 button switch.