--- a/services/sync/modules/policies.js
+++ b/services/sync/modules/policies.js
@@ -168,20 +168,22 @@ SyncScheduler.prototype = {
         // should still be updated so that the next sync has a correct interval.
         this.updateClientMode();
         this.adjustSyncInterval();
         this.nextSync = 0;
         this.handleSyncError();
         break;
       case "weave:service:backoff:interval":
         let requested_interval = subject * 1000;
+        this._log.debug("Got backoff notification: " + requested_interval + "ms");
         // Leave up to 25% more time for the back off.
         let interval = requested_interval * (1 + Math.random() * 0.25);
         Status.backoffInterval = interval;
         Status.minimumNextSync = Date.now() + requested_interval;
+        this._log.debug("Fuzzed minimum next sync: " + Status.minimumNextSync);
         break;
       case "weave:service:ready":
         // Applications can specify this preference if they want autoconnect
         // to happen after a fixed delay.
         let delay = Svc.Prefs.get("autoconnectDelay");
         if (delay) {
           this.delayedAutoConnect(delay);
         }
@@ -800,23 +802,25 @@ ErrorHandler.prototype = {
         break;
 
       case 500:
       case 502:
       case 503:
       case 504:
         Status.enforceBackoff = true;
         if (resp.status == 503 && resp.headers["retry-after"]) {
+          let retryAfter = resp.headers["retry-after"];
+          this._log.debug("Got Retry-After: " + retryAfter);
           if (this.service.isLoggedIn) {
             Status.sync = SERVER_MAINTENANCE;
           } else {
             Status.login = SERVER_MAINTENANCE;
           }
           Svc.Obs.notify("weave:service:backoff:interval",
-                         parseInt(resp.headers["retry-after"], 10));
+                         parseInt(retryAfter, 10));
         }
         break;
     }
 
     switch (resp.result) {
       case Cr.NS_ERROR_UNKNOWN_HOST:
       case Cr.NS_ERROR_CONNECTION_REFUSED:
       case Cr.NS_ERROR_NET_TIMEOUT:

--- a/services/sync/modules/resource.js
+++ b/services/sync/modules/resource.js
@@ -280,23 +280,27 @@ AsyncResource.prototype = {
       channel.visitResponseHeaders({
         visitHeader: function visitHeader(header, value) {
           headers[header.toLowerCase()] = value;
         }
       });
 
       // This is a server-side safety valve to allow slowing down
       // clients without hurting performance.
-      if (headers["x-weave-backoff"])
+      if (headers["x-weave-backoff"]) {
+        let backoff = headers["x-weave-backoff"];
+        this._log.debug("Got X-Weave-Backoff: " + backoff);
         Observers.notify("weave:service:backoff:interval",
-                         parseInt(headers["x-weave-backoff"], 10));
+                         parseInt(backoff, 10));
+      }
 
-      if (success && headers["x-weave-quota-remaining"])
+      if (success && headers["x-weave-quota-remaining"]) {
         Observers.notify("weave:service:quota:remaining",
                          parseInt(headers["x-weave-quota-remaining"], 10));
+      }
     } catch (ex) {
       this._log.debug("Caught exception " + CommonUtils.exceptionStr(ex) +
                       " visiting headers in _onComplete.");
       this._log.debug(CommonUtils.stackTrace(ex));
     }
 
     let ret     = new String(data);
     ret.status  = status;