some radiators not getting hot

hi i have a glow worm fire and back boiler weve had a few promblems burst hot water cylinder new pump.weve drained down and now we have some cold rads.bled all rads a number of times but still no joy can anyone suggest anything thanx

run the heating system, close one valve on each radiator that gets hot... hot water should force its way to rads previously cold... as these start to get warm shut them down until one rad is left... dont close that vave though. Bleed all rads and job done!
Sometimes temporarily turning the pump speed up helps, but remember to put back to original setting.

Strictly speaking the radiators need balancing after this, especially if no TRV's fitted...

thanx for that trying that now,,how do you balance the rads??tried turning all the hot ones of the cold ones get hot but then go cold when turn others back on??????