Thank-you all and no I haven't dismantled it as yet. It may just need a good clean? I do 1 hive and it won't work for quite a while until it is almost completely cold. I have replaced all the connectors so this is the next thing.
Nearly all glow plugs are around the 50W mark. Modern ones are 12 volt. Induction heaters (usually used in larger commercial applications) can be 24 volt and higher powered.
Older engine designs used 3V glow plugs in series. A B when one failed.��