Can I suggest that you take the can of WD40 out of the toolkit?
It is not a lubricant as most people think but a waterproofing agent. If you spray some on a clean surface it will dry out to a sticky brown wax. Because it sticks dirt so any contacts, it makes most electrical problems worse. Replace it with a spray can of 3 in 1.https://www.ebme.co.uk/forums/images/icons/default/thumbs_up.gif