johno1234:

 

Bananabob:

 

How do I know if the plug that goes into the HP switch is the correct way round (is it called polarity?) that is where the negative and positive are? (Sorry a bit dumb on this sort of thing)

 

 

Your closeup image of the label shows that the centre pin is +ve. That's the most common so you should find that any generic ones have the same picture.

 

 

 

Thank you, and any amp rating as long it's 12V?