8mm microbore flow & return pipes into one valve only. 3 out of 6 rads will work the others do not. Due to this strange valve configuration I stripped and cleaned the rad, valve and length of pipe attached to the valve which inserts into the rad and flushed the rads. reassembled all & refilled the system without success....Possible microbore blockages and if so the best possible solution to clean through. Bent microbore??? Manifold failure ??? 12 outlets on one manifold presumably 2 x six rads but all on one 22mm single pipe (returned) both into and out of the cylinder. Could the rads be Knackered and require replacement??? On one occasion I tapped a valve and the rad came on albeit the valves are simple and now clean and appear to be ok?? Any other tips or assistance would be appreciated.. NOTE **** The hot flow is getting to the valve in all instances but not heating the rad and susequently no return.