actually the cap of the "pad" comes off, but doing so isnt for those with heavy hands or who is lighthearted. the cap is the only part visible when assembled protruding from the "control surface" area. but disassembled the cap should be an easy recognizable part of the switch assembly. you want to get good upward pressure from both sides of underneath the "pad" cap with small screwdriver or knife or other thin tool without applying much down pressure if its assembled since you dont want to damage the "control surface". slow and steady but firm pressure upwards will dislodge the cap of the switch with some finesse and patience.
I actually paid Forat to do mine, which I requested new switches for all drum "pads". But he was very adamant about wanting to clean the serviceable ones and only replacing the ones which are absolutely necessary to replace as the switches are in very limited supply these days. I ended up only getting one switch replaced and the rest cleaned/serviced. All are now much more responsive feeling than before servicing, but you can slightly tell the difference between the old "pads" and the newly replaced one.
once inside the switch mechanism there is an arm type mechanism which lays across a spring and has a contact point on the other side. hopefully your spring is in good condition. if not you may want to order a new switch if you can locate one. anyway. blow the switch out with compressed air and/or swab out with a q-tip and some 91+% isopropyl to clean out any particulate debris which may have found its way inside over the past few decades. then you would want to identify the switch contact points and clean them up with either a deoxidizing solution and/or manually scraping with a metal tool so that the contact points are clean of any corrosion. the contact point and underside of the arm thingamajig need to be clean so as to allow unobstructed conductivity. reinstalling the cap to the switch mechanism should be self explanatory. just keep in mind that patience and being firm yet gentle are the key with these virtually irreplaceable machines/components.
there is also a "hack" of sorts which involves installing a paper/cardboard
SHIM type piece of material inside the cap of the switch mechanism just to take up a very small bit of distance between the plastic cap of the "pad" and the arm mechanism that contacts the contact point beneath it so that it takes less pressure to actually make contact and allow conductivity between the 2 points without having to impact the "pad" with as much pressure as usual.