You can buy a "Solenoid Stem Kit" from any heating Component stockist such as partscenter, turn off the oil supply to the burner, remove the brass nut ontop of the coil (4mm Allen Key) remove the coil, this will expose the Stem, undo the stem using 10mm ring spanner, fit new stem in reverse order will take about 5mins
www.elanar.co.uk, March 2010