diff --git a/playbook/shopfloor-setup/gea-shopfloor-waxtrace/09-Setup-WaxAndTrace.ps1 b/playbook/shopfloor-setup/gea-shopfloor-waxtrace/09-Setup-WaxAndTrace.ps1
index be7fe63..5b419b4 100644
--- a/playbook/shopfloor-setup/gea-shopfloor-waxtrace/09-Setup-WaxAndTrace.ps1
+++ b/playbook/shopfloor-setup/gea-shopfloor-waxtrace/09-Setup-WaxAndTrace.ps1
@@ -224,9 +224,24 @@ if (Test-Path -LiteralPath $mnPath) {
 if (-not $asset) {
     Write-WTLog "machine-number.txt missing or empty - skipping calibration apply" 'WARN'
 } else {
+    # Consistency: a per-asset backup ZIP (restored in Step 3b with HKLM + data
+    # + config, including the probe cal tables) is the single authoritative cal
+    # source. When one is staged - true for every migrated bay - skip the
+    # redundant, fragile cal-ISO mount/vendor-Setup path so all bays follow one
+    # flow (app ISO + backup restore), same as bays that never had a cal ISO.
+    # A future bay with a cal ISO but no backup still falls through to the ISO.
+    $haveBackup = @('C:\WaxTrace-Install\backups','C:\WaxTrace-Install\backup') |
+        Where-Object { Test-Path -LiteralPath $_ } |
+        ForEach-Object { Get-ChildItem -LiteralPath $_ -Filter "${asset}*.zip" -File -ErrorAction SilentlyContinue } |
+        Select-Object -First 1
     $calDir = Join-Path $stagingRoot 'calibrations'
-    $candidate = Get-ChildItem $calDir -Filter "CAL-${asset}_*.iso" -ErrorAction SilentlyContinue | Select-Object -First 1
-    if (-not $candidate) {
+    $candidate = $null
+    if (-not $haveBackup) {
+        $candidate = Get-ChildItem $calDir -Filter "CAL-${asset}_*.iso" -ErrorAction SilentlyContinue | Select-Object -First 1
+    }
+    if ($haveBackup) {
+        Write-WTLog "Per-asset backup ZIP present ($($haveBackup.Name)) - skipping cal ISO; calibration restored from backup (Step 3b)"
+    } elseif (-not $candidate) {
         Write-WTLog "No cal ISO matched CAL-${asset}_*.iso in $calDir - skipping" 'WARN'
     } else {
         Write-WTLog "Mounting cal ISO: $($candidate.FullName)"