What can I use to lubricate electrical contacts?
I suggest the use of a `dielectric grease'. In particular, look for one compatible with high temperature, which are often made out of silicone. The grease can be ordered online, but would also be available at many auto-parts stores.

One requirement of this application is that the lubricant must not be electrically conductive. If a conductive lubricant is used, it would be a fire hazard. Dielectric means that it wouldn't conduct electricity.