I replaced ours, fairly straight forward. I have NO mechanical experience until I bought this rig... You might want to change the solenoid at the same time (cheap and easy).
Our issue is the bearing on the pump... A new one comes with the motor, but we couldn't get the old one out and now it's seized. The pump is a MUCH bigger deal and we can't find anyone to work on it?! Been without jacks all summer and really getting frustrated. Unfortunately, from the hours of research I've done the grinding sound is usually the pump bearing. Be sure to clean that unit up and get the new one in.
I found an old post about rebuilding one of these here on IRV2 that linked to a member's blog showing a good breakdown of replacing the system.
https://www.1999southwind.com/levele...ll-of-marbles/
Hope this helps and good luck!