Brushroll motor on a DC24 is an easy fix. Same with the DC25/40.
As a general rule, the newer the model, the more complex and expensive they are to fix. Once the whole range became ball models, accessing the main motors got far more difficult and expensive. I think I've only ever replaced a main motor on a couple of ball models, as it's so time consuming.
By comparison, the DC1/DC04/7/14/33 are extremely simple, and even the motors are only about £20. Almost all parts are still available for these.