This is why it is very important to pay attention even on the small parts. Because oxidised connectors have a higher electrical resistance and therefore will heat up more easily. This power then is missing on the other end of the cable. For example on the main beam lamp. (may be this is why they are sometimes so dim.)
Also it is important to have an eye on the several earthing points. Often the rustworm starts here. It is essential to have earthing points on blank metal.
The relevant connectors can be found here: