Yea try bleeding all the radiators, and turn them all off. Then what i usually do is turn on/open the radiator valves, closest to the boiler and wait till that one gets hot, then open the next one and turn off the first. keep going until all of them have become hot, and empty of air,(bleed them as you go too) then turn them all on in the same order as you did before. hopefully by doing this you would push the air blockage through to the last rad where you can remove it.
hope this helps