Neither normal nor abnormal. There are many different ways it can fail from noises, roughness and binding, and intermittent lack of power assist, especially when cold. The most common failure is a leak.
The good news is there are rebuilt assemblies available from aftermarket companies that do a real good job of improving the high-failure items, and they're very inexpensive. Rebuilt racks often cost around $150.00, about one third of the price for a new one from the dealer.