Ferroli F30 Combi Boiler, Pump Continious Running? Advice pl

[D1manutd]

had few problems with my combi,pcb board was damaged,Changed it,Then kept blowing fuses on pcb board checked pump,disconected lead from pcb board,to pump,hot water work fine,not blowing fuses now,got second hand pump tested ok,put pump on,and ran,working fine,but dosent appear to shut down,boiiler runs,get to temperature,cuts off,but pump still runs,and appears to be getting very hot ?? any help would be greatly appreciated Thanks