I respect but can’t wholly endorse the advice offered. I do agree that a thorough review of the case file is appropriate; without it, the OP may not fully appreciate the “legal remedies” available.
An AZ judgment is initially effective for five (5) years from the date of its entry by the Clerk of the Court. The OP is released from further obligation unless the judgment creditor files an affidavit of renewal or brings an action for enforcement during that period. (A.R.S. §12-1551).
While five years may be a comparatively long time, if the OP seeks to vacate the judgment and vacating a judgment commonly requires a “prompt response without undue delay”, under the circumstances posted, any response at the moment may be “poking the bear”. We might infer that there has been no enforcement effort since judgment was entered. We do not know if the five years has been exceeded. We do not know if the judgment has been renewed and we do not know the OP’s ultimate goals under any scenario. We also do not know what is intended/expected by “fix the issue and reapply”.
We do not know if judgment lien(s) were recorded, but it is a reasonable assumption that they were, since the OP became aware of the default when attempting to purchase real property. To reiterate what was already stated, we do not know the present viability of any such liens but it is worth noting that, should the OP successfully vacate the judgment and unsuccessfully litigate the original claim, it is highly probable that the property sought to be purchased will be promptly burdened with a lien (see A.R.S. §§ 33-963 and 33-964). Again, “poking the bear” may not be wise.
If the OP were to successfully vacate the judgment but unsuccessfully litigate the original claim, there will be five more years of accrued interest on the claim, possibly making settlement without suit more difficult.
The claimant will not have to “find and serve” the OP, as suggested. Any disputed issues are simply re-opened and litigated on the merits. To get the judgment vacated and to have that opportunity, the OP will have to show the claimed defect in service and a valid defense.
The OP is trying to strategize to make what is commonly regarded as one of the most significant financial decisions made in the average lifetime. My advice would be to forego anonymous internet strangers and contact local counsel for further assistance