Worcester 240 RSF overheat activating intermittently

Hi battle , with this type of fault I always put heating on to eliminate slow running pump or partial blocked main heatexchanger. You can read on digital temperature / or just feel with hands either side of plate to see temperature differential ,to see if plate heat exchanger is blocked. Always a good method. I’ve even had faulty overheat stats give problems aswell, good clean up and new heatsink paste to eliminate that, and check with multi meter.Ive had no water in boiler👻stuck pressure gauge reading 1 bar given same symptom, These are my methods on a general basis for all boilers,but some individual boilers does have funny knacks! IE blocked filters , black hoses.