Pro tip: Manual focus checks often work better than digital tools
Many camera repairers say you must use digital calibrators for lens focus issues. I disagree from my own work. I have fixed lots of lenses by just using a printed test chart and looking through the viewfinder. This way, I can feel the adjustments and see the results right away. It works for old film cameras and newer digital ones too. Sure, those fancy tools are good for very tricky autofocus problems. But for most repairs, like sticky focus rings or slight misalignments, my method is faster and cheaper. I have had happy customers for years without needing expensive gear.