I helped in stall a couple STI belts. I would honestly be surprised if they did not get a million cars, if they are well maintained. And they have the belt flush system.
i know where to get some new stainless steel rails for a short machine at a reasonable price, they were ordered long ago, and then the buyer backed out.
More details? When you say every four to six weeks, how many times have you done this? Sometimes I have had chains do this, and then return to the less often frequencies...check the "dog bones" do they seem pretty worn? replacing just those is an option.