All unexpected damages are fully covered at no cost to you. You will be charged nothing for the fix and fully reimbursed for the shipping cost. Unexpected damages are things like
-z button switch stops working
-phob board shorting
-button getting jammed etc.
All expected damages are not covered, these include:
-PODE (potentiometers degrading over time)
-stickboxes, notches, and stick caps wearing down over time
These are unavoidable phenomenon and can be fixed for a low cost, but are not covered for free.