I was about to give up on my trusted Hitachi C10FS SCMS that I'd bought a long time ago when they first came out. It has been rock solid for a very long time, hitting 45 and 90 degree angles as exactly as I could measure them. In the last 12-18 months I'd begun to have problems with slightly out-of-square cuts, getting progressively worse.

My thought was that I'd used it so much that I'd worn out the detent mechanism and it had gotten sloppy. I decided to take the saw apart to see if there might be a replaceable part to return it to its former accuracy. On disassembly I saw that the detent mechanism used a spring-loaded ball bearing dropping into a beveled hole. That seemed like a really nice design with not many ways to go wrong. As I cleaned it up I noticed that there was an accumulation of ancient grease and sawdust in the detents. I cleaned all of that out and lubricated with a light coating of new grease and put it back together.

As if by magic it once again popped into exact cut angles-- problem solved. Perhaps I won't wait twenty years before cleaning it the next time. Now I can think about what else to do with the kilobuck or so I might have spent on a new saw!