Yes I did replace my spring bar bushing but not at the time I re-did the hitch. I replaced them a year ago this summer. The cost was not cheap, around $35 or maybe a bit more, don't remember for sure. You also need to send them your old bushing so don't throw it away. They will charge you a deposit fee and then when you send your old one back they refund the fee.
In your case, since you purchased yours used, I doubt whether you have warranty so you may not need to send your old one back. Call them before you order and ask. You can tell when it needs replacing when the bottom is oval'ed out and the thickness of the walls is not even.
Barney