diff --git a/src/proc/engine/engine-diagnostics.hpp b/src/proc/engine/engine-diagnostics.hpp
index bbb4052fb..be4e50859 100644
--- a/src/proc/engine/engine-diagnostics.hpp
+++ b/src/proc/engine/engine-diagnostics.hpp
@@ -43,7 +43,7 @@
 //#include "include/display-facade.h"
 //#include "proc/engine/calc-stream.hpp"
 //#include "proc/mobject/model-port.hpp"
-//#include "proc/play/timings.hpp"
+#include "proc/play/timings.hpp"
 //#include "proc/play/output-slot.hpp"
 //#include "common/instancehandle.hpp"
 //#include "lib/singleton-ref.hpp"
@@ -62,6 +62,7 @@ namespace engine{
 //    using lumiera::Subsys;
 //    using lumiera::Display;
 //    using lumiera::DummyPlayer;
+  using proc::play::Timings;
   
   
   
@@ -93,6 +94,13 @@ namespace engine{
           TODO ("detach tracing connector");
           engine_.disableTracing();
         }
+      
+      /** */
+      bool
+      has_scheduled_jobs_for (Timings const& timings)
+        {
+          UNIMPLEMENTED ("Engine Diagnostics: query scheduled jobs");
+        }
     };
   
   
diff --git a/src/proc/engine/engine-service.cpp b/src/proc/engine/engine-service.cpp
index b85353211..e9d188a78 100644
--- a/src/proc/engine/engine-service.cpp
+++ b/src/proc/engine/engine-service.cpp
@@ -106,8 +106,7 @@ namespace engine{
   class PriorityQoS
     : public DefaultQoS
     {
-      CalcType type_;
-      
+    
     public:
       PriorityQoS ()
         : DefaultQoS(PLAYBACK)
diff --git a/src/proc/play/diagnostic-output-slot.hpp b/src/proc/play/diagnostic-output-slot.hpp
index e0e4a7f0a..b699e0ae8 100644
--- a/src/proc/play/diagnostic-output-slot.hpp
+++ b/src/proc/play/diagnostic-output-slot.hpp
@@ -62,6 +62,14 @@ namespace play {
     : public OutputSlot
     {
     public:
+      /** build a new Diagnostic Output Slot instance,
+       *  discard the existing one. Use the static query API
+       *  for investigating collected data. */
+      static OutputSlot&
+      build()
+        {
+          UNIMPLEMENTED ("Diagnostic Output Slot instance");
+        }
       
     private:
       
diff --git a/tests/components/proc/engine/engine-interface-test.cpp b/tests/components/proc/engine/engine-interface-test.cpp
index be9ec028b..fd55ee76f 100644
--- a/tests/components/proc/engine/engine-interface-test.cpp
+++ b/tests/components/proc/engine/engine-interface-test.cpp
@@ -27,6 +27,7 @@
 #include "proc/engine/calc-stream.hpp"
 #include "proc/engine/engine-service.hpp"
 #include "proc/engine/engine-diagnostics.hpp"
+#include "proc/play/output-slot.hpp"
 #include "proc/play/diagnostic-output-slot.hpp"
 #include "proc/mobject/model-port.hpp"
 #include "proc/asset/pipe.hpp"
@@ -47,8 +48,11 @@ namespace test  {
   using asset::Pipe;
   using asset::PPipe;
   using mobject::ModelPort;
+  using proc::play::OutputSlot;
+  using proc::play::DiagnosticOutputSlot;
   
   typedef asset::ID<Pipe> PID;
+  typedef OutputSlot::Allocation Allocation;
 
   
   namespace { // test fixture...
@@ -84,7 +88,7 @@ namespace test  {
           
           EngineService& engine = EngineService::instance();
           EngineDiagnostics monitor(engine);
-
+          
           PID pipe = Pipe::query("id(dummy)");
           ModelPort port(pipe);