How do I fix my Keystone slide, they won’t do it!

To do a proper job, you really need to completely remove the slide get it on the bench so to speak and rebuild it properly. Once out you will likely find way more damage than you are seeing now. At least this will give you the opportunity to do the job right. Done too many jobs the hard way. It usually winds up costing me way more time and effort than is required to do it right.