Pinging sound on red cherry MX and opening switches

[pheo]

Hi guys, it's been a while...
I have a filco minila with red switches, but some keys do a loud and annoying pinging sound. So I have thought of applying grease to the springs. I have read some tutorials on the forum on how to open Mx switches, I have tried to open one but I suspect that I can't open the switches without disassemblying the switch from the plate, am I right? So I don't want to de solder the switches to open it.
What is the right way to oil the switches mounted in the plate?
Some tips to reduce the pinging sound?
Thanks a lot.
Kind regards!