boiler lights, but just ticks over, IE: it won't go to full flame?
 
                The boiler is a Radiant RS24. It lights, but stays on tickover. We've had a new pcb, limit thermostat and heating sensor fitted and it is still the same. 
Note: Before we replaced parts, if we shook the control panel with the PCB in, the flame rose to full. 
Any ideas as to what's causing the problem?
            
             Steve
            
 September 2010