So, do you bring your watch in to be repaired? Do you take your shoes to a cobbler to be re-soled? No, it doesn’t make sense to pay for the high cost of repairs (if even available) unless you have designer shoes or a Rolex watch. Like the rest of us, you throw them out and buy another.
So, what has this got to do with wheelchairs? Same strategy! The chair's components are manufactured to fail after a certain length of time or mileage so that additional parts and/or labour can be charged and shareholder profits extended. I have replaced just about every component on my wheelchair and everything has failed after the one year warranty expired!