diff --git a/etl/hubspot/hubspot_deal_differ.py b/etl/hubspot/hubspot_deal_differ.py
index 60aece16c..bb1e58674 100644
--- a/etl/hubspot/hubspot_deal_differ.py
+++ b/etl/hubspot/hubspot_deal_differ.py
@@ -320,11 +320,11 @@ class HubspotDealDiffer:
 
         new_survey_date = parse_hs_date(new_deal.get("confirmed_survey_date"))
         new_survey_time = new_deal.get("confirmed_survey_time")
-        # HubSpot sends "" for an unset property; the DB stores None. Treat
-        # them as the same so a booked deal doesn't amend on every scrape.
-        raw_surveyor = new_deal.get("third_party_surveyor_identifier")
-        new_surveyor = (
-            raw_surveyor if raw_surveyor is not None and raw_surveyor.strip() else None
+        new_surveyor = HubspotDealDiffer._normalised_surveyor(
+            new_deal.get("third_party_surveyor_identifier")
+        )
+        old_surveyor = HubspotDealDiffer._normalised_surveyor(
+            old_deal.third_party_surveyor_identifier
         )
         logger.info(
             "Abri job-amendment check: "
@@ -336,7 +336,7 @@ class HubspotDealDiffer:
             new_survey_date,
             old_deal.confirmed_survey_time,
             new_survey_time,
-            old_deal.third_party_surveyor_identifier,
+            old_surveyor,
             new_surveyor,
         )
 
@@ -354,7 +354,7 @@ class HubspotDealDiffer:
         if old_deal.confirmed_survey_time != new_survey_time:
             return True
 
-        return old_deal.third_party_surveyor_identifier != new_surveyor
+        return old_surveyor != new_surveyor
 
     @staticmethod
     def check_for_abri_tenant_data_fetch(
@@ -420,6 +420,14 @@ class HubspotDealDiffer:
         old_outcome = (old_deal.outcome or "").lower()
         return new_outcome == "surveyed" and old_outcome != "surveyed"
 
+    @staticmethod
+    def _normalised_surveyor(value: Optional[str]) -> Optional[str]:
+        # HubSpot sends "" for an unset property and the DB stores whatever
+        # the scrape wrote, so blank and missing must compare as equal.
+        if value is None or not value.strip():
+            return None
+        return value
+
     @staticmethod
     def _is_abandoned(
         number_of_attempts: Optional[str], outcome: Optional[str]