You can disassemble the switch housing with the 4 phillips screws on the underside, and the buttons will twist apart. Careful to keep track of the interior bits and their orientations... The contacts on the buttons get a little crusty and so do the washers. A quick scuff and some dilectric grease and you should be good to go. It's also a good idea to separate the connectors and pop the pins out to do the same.
Protip: if you own a pool, a quick dip in muriatic acid, rinse/wipe and grease goes a LONG way. Learned it from an old head and I've been using that trick for years. Pins pop out easy with a little tab on the inside of the connector. A cheap pin-pusher off amazon is a solid investment too. $8 tool has saved my ass plenty
