Hi,i have a baxi bahama 100 with a fault,it has had both flow switches replaced,main pcb replaced,ignition pcb replaced recently,now it has been working fine for the last few weeks but has now has started on occasion to run for a while then starts to cut in and out every few seconds,this happens in dhw mode and c/h mode,the only way to stop this is to switch it off,there is no flame failure light or lockout.any help would be great.Thanks. 