it is most likely 6 years old. And with the motor working that hard..

if it is full then you should pull (or climb under) and check the 4 sensors / rings for obvious damage. Clean the rings, etc.

checking the condition of the brakes would be good as well, if one of the drums is not stopping it will do this, and you might not feel it in the car. I think you need to pull the drum to get to the ring too..

it a lot of work though, so its up to you whether you spend a day pulling it apart to hope to see something, or try to get it scanned to a direct repair. because the pump could also be bad.. and you'll not find that yourself.