Use the crc to clean all the grease and dust off.
Some dental brushes/ mini bottle brushes sold at pharmacies in the dental care section can help dislodge old grease, and clean along with teh crc.
CRC does nothing for oxidation on the contacts however.
Caig DeOxit d5 spray is kind of like magic electrical juice. After the crc is done, this stuff sprayed in the contacts, and abraded with the bottle brushes, when wiped on a white napkin, will reveal all that which the crc missed.
The caig is too pricey to use as a degreaser.
Get some Dielectric grease for mating the connector to keep moisture out.
The grease on the spring loaded contacts of the rocker switch might not be a great Idea.
Caig does have a Shield S5 spray, but this might be a bit overkill to buy just for this task.
But the D5 spray should be acquired and used on all sensor connector contacts and anywhere electrical contact is questionable. It's a really good product to have.
Try some on the charging plug of your phone and you will remember how it felt when it was new. It will likely charge faster too.https://caig.com/deoxit-d-series/