What comes to mind when you hear the word "tinker"? Years ago, before the major advances in custom tooling and gaging, it was common for homeowners to fiddle with their tools and gadgets to make minor adjustments and repairs on a mechanical level. In fact, this was a pretty indispensable skill not too long ago. People frequently repaired their vacuums, blenders, coffee machines, power tools, lawnmowers, and other home appliances. So what, exactly, needed repairing on these devices?