Collets are precision devices and a few thousandths wear and they no longer work. You can try ereplacementparts.com, but as mentioned, we get a lot of requests for collets on old gear, and most of the time, they're not available. You can contact Porter Cable but they were bought out and don't seem to be carrying old parts based on posts here. I am also a Bosch fan. I also have three, two 1617s and the Colt trim router. Hard to beat the 1617 kit. And I just don't buy used tools because I'd rather make stuff than try to find parts.