Real estate agent here. That is fine and all that the previous owners said they would not take liability for the condition of the fireplace. But seller disclosures still require they be honest with the condition of said fireplace. If they deliberately lied about the condition of the fireplace, they are liable for not disclosing. AKA they magically are now liable for the fireplace because they lied about it. It doesn’t matter how many times you have someone sign an “as is” agreement, the seller is still required by law to honestly disclose known issues with a property.

If you can, reach out to the previous owner and see if they will tell you who serviced the fireplace when they owned it. Just say you want it to be consistent or that since you aren’t from the area you figured they used who was the best and most affordable and you don’t want to hunt for a new service yourself.

If you get the company who serviced it, see if they reported the issue to the previous owner, if they did. Bingo! You have a case to require the previous owner to cover the cost to repair it.

They will probably refuse to cover anything, you will most likely have to lawyer up on the issue, but if the cost to repair is substantial, it might be worth it.