Collets are high precision items, less than a mm off and they're useless. They eventually wear out on all brands and need replacement. Unfortunately it is a Craftsman item and those parts are really hard to come by. Try https://www.ereplacementparts.com/cr...-c-158286.html
If it were me and found the right parts, I'd order several because Craftsman is now part of Stanley, and not many parts will be around for long. Stanley has become something of a scavenger, eating up once proud brand names to exploit
In which case, I'd seriously consider buying a Bosch 1617 EVSPK kit with router, fixed and plunge base, plus a half and quarter inch collet. Bosch is serious about their tools' quality and parts availability. You can also use the fixed base to mount the router under a table and you can get an inexpensive key to make fine height adjustments while It's under the table. Routing on the table is almost always safer than freehand. The plunge base is what you'd use for freehand routing.
There are all kinds of accessories for the 1617.
Making a router table can be a very simple project, and you can read about it by searching for shop made router tables.
Read the stuff Stick sent, lots of good information. Since you're getting back into woodworking, you might also enjoy reading the attached article on the 17 things that accelerated my learning curve. Including some heads up on some costly mistakes I made that may save you the trouble and expense.
The pictures show the 1617, first the contents of the EVSPK kit, the second as it fits under a table. Last is the pdf for download.