The ones that get weak and break are usually something like a flipper EOS switch where it has super-high use, is flexed farther and is likely to have been over-adjusted by someone worse than a motor switch. If it's still happening after the above mentioned tightening of the stack and it really is worn out, you could open the switch stack at that point and either replace the switch blade or add a second switch blade (with the point end snipped off) behind or in front of it depending on which direction you need more stiffness. When adjusting, make sure the switch adjuster tool is as close to the stack as you can get it.