I have just solved this problem on our bosch machine.At the conditioner stage of wash water runs in via the solenoid valve into the top spray compartment above detergent/conditioner draw.Two small holes above the conditioner compartment should pass water into the draw,thus diluting and then syphoning liquid into drum.I found the two small square holes where blocked,with what looked like black mould,causing the water to take the easier route accross into the detergent draw inlets. The holes can be cleared by pushing a lenth of wire up into the holes with the draw out,pushing and pulling in an attempt to clear the channels.I also removed lid of machine and removed the two cold water rubber hoses from the top rear of water inlet camber/draw( held with spring clips,just squeeze with pliers) and pushed wire in from both ways to clear muck in inlets.Now all is OK. This build up of mould/muck is probably caused by low temp washes ,might be a good idea to run very hot washes now and again,allowing the hot inlet water to help keep things clear,no good on late machines as only cold fill.hope this helps
Len Saunders, October 2008