Well, not quite. I took it apart because I had already sprayed it with 3 different kinds of contact cleaner at least 5 or 6 times and still intermittent contact. Worse yet, I didn’t actually find anything wrong... but it worked perfectly after I scrubbed and sprayed it with food grade silicone spray lube.
It wasn’t until a few days later when I was editing pix I took during the work that I found the one pic right after I’d removed the plunger clearly showing a tiny grain of sand which had gotten in there.
Just proof that sometimes, following a known effective procedure consistently is as important as diag and inspection results.
In this case, it is my opinion that the switch is made this way on purpose such that it can be serviced this way. I see no good reason not to take advantage of the fact to give it a good scrubbing every once in a while.
mnem
As a rule you should NOT use silicone lubricants on contacts. If there is any arcing at the contact Silicon Dioxide (glass) can form ruining the contact. Some contaminants can also cause silicone to form solid insulating layers on contacts. If you get even tiny amounts of silicone near contacts it can cause issues. One case was the UK Post Office Telephone exchanges (Old Strowager type) where thy had problems eventually traced to the floor polish changing to have silicone wax in it.
A good grease lubricant for contacts is petrolum jelly "Vaseline". Mixing in a little oil based contact cleaner makes it even better.
I disagree where self-cleaning/wiping contacts are concerned; particularly pots & sliders. 3 decades of empirical experience points to the contrary, and petroleum jelly is flammable (in an arc-flash situation it breaks down creating flammable vapors which can ignite/scorch surrounding plastic), where the microscopic residue from a good food-grade silicone spray is not. Its hydrophobic nature also inhibits issues from moisture in the air.
Use what you choose to; I'll stick with my food-grade silicone. If I'm wrong in that, OFW.
In this case, if you're worried about the silicone spray (or you don't know which of the dozens of such spray concoctions out there is a good choice), just scrub/flood the thing with alcohol as seen in
my pictorial and run it dry like it came from HP.
mnem