The self lube ability in these gears is a porous metal gear (brass or bronze like) lubricated with a specific grease. When the machine get's used the lubrication heats up and release enough to keep it running fine. This type of lubrication should not be impossible to replace, it's a well know technology. If replacement parts are available, it's worth it, but it all depens upon what you are willing to pay or spend time on as a DIY project.