If your fiber optic is held in place on both ends and in the middle you can easily replace it yourself. I am pretty sure the dia is .060" but you can check it. All you do is snip it in the middle and pull out each end. Cut a length about 3/2" longer than you need. Heat one end to soften it a bit and press it gently against a solid surface to form a tiny button. Push it through the sight and cut it about 1/16" longer than flush. Heat and flatten that end slightly (remember to hold the other in in place while you do so.) This actually takes longer to explain than to actually replace.