Pianos are composed largely of natural materials, and the wood, leather, felt and other parts can begin to dry out and break. Many parts can be repaired or replaced. Repair work can be assessed on a case by case basis, and I would be happy to discuss the appropriate course of action.
Some repair work can be done on the spot, but sometimes it requires more extensive effort that requires the action returning to my workspace.
There are certain things in the action the require periodic attention to maintain the instrument. Hammer filing shold be done when the grooves in the hammers start getting deep. While this is an operation that requires the action to come back to the shop, it is a regular part of piano maintenance.