The last of the Analog transformers made by Marklin is the #6646/6647 30 Watt unit. Over the years I’ve sold more than one hundred of these. I would take them from Starter Sets and sell all of the other components separately. That kept the cost down for the customers. You can still get one, but since all Marklin Starter Sets are now Delta (Digital) and don’t have a #6646/6647 a new one is very expensive.
During the last year I have had to fix three. Seems that the track voltage stopped working. The fixed output for accessories was fine. Long story short I found that the wire connecting the control knob to the internal coil had broken. All three were fixed and returned to their owners for a lot less than a new one would cost.
This tip is about opening the transformer for repair and then sealing it back up. To open the transformer requires the removal of 4 plastic pins (two on the right side & two on the left side). This is very easy – just get a 3/16″ Drill Bit and carefully drill into the 4 plastic pins to a depth of 1/4″ to 3/8″. When you have done that the cover should just pop open. The rest of the pins can then be removed from the inside frame with pliers.
After the internal repair is made and the case is put back together I use plastic Golf Tees to replace the pins. Insert one in each of the four holes and tap them in with a small hammer. There should be a tight fit and no glue should be required. The last step is to use an X-Acto Razor Saw to cut the Tees off flush with the case. I prefer Red Tees but you can use any color you want.