I've got a 2017 PSE Evolve and recently noticed that there's a missing "O" ring from one of the roller glide spindles and by the looks of it the 2nd ring is not going to last much longer. Can't seem to find the specific part number or even mention anywhere about that specific of a piece to replace it. Anyone know how necessary those rubber "O" rings are? I've seen other brands of similar roller slides and it doesn't look like some of them even have those rings. Appreciate the help.