If the manual suggests a blocked pipe then it means the water is not draining out when it should, so - either the outlet pipe is blocked, or the pump has got a sock or something in it stopping it to turn, or the pump motor has burned out, or the pipe from the drum to the pump is blocked with a sock or something.
If you remove the outlet pipe you should be able to blow down it (clean it first) and hear the air come into the drum if the door is open or you could also connect a water pipe to the outlet and see if the water goes back into the machine, it will normally go back through the pump if it is not blocked.