For the last year or so, the oven temperature control on our Kenmore gas stove has been decreasingly stable, sometimes varying by 100 °F from the setpoint before settling down somewhere close to what it should be. Spotting a replacement control board for a bit over $100, I decided the board used an absolute rotary encoder of the open-frame variety, so I took the thing apart:
The encoder was, indeed, an open frame:
The red droplet is DeoxIT, the rest of which went inside, just ahead of the contact fingers, and got vigorously massaged across the switch contacts on the wafer by spinning the shaft.
Some time ago, the membrane over the TIMER ON/OFF switch cracked and I applied a small square of Kapton tape. Having the entire controller in hand, I replaced the square with a strip of 2 inch Kapton, carefully aligned with the bezel marks embossed on the membrane, and now it’s smooth all over:
The MIN(ute) ^ switch required a much firmer than usual push, so I tucked a shim cut from a polypropylene clamshell between the membrane and the pin actuating the switch.
Reassembled, it works perfectly once more.
Gotta love a zero-dollar appliance repair!
The Smell of Molten Projects in the Morning 
I really dislike those membrane touch controls. Sooner or later, the membrane is gonna break or crack. So I admire your figuring out a repair.
2 years ago, we replaced our 30 year old GE combo microwave/oven. It had a glass touchpad which never gave us a problem. While looking for a model to replace it with, I noticed that many/most use membrane touch controls, but some had glass controls. The ovens with glass controls tended to cost a bit more (usually because they were on models that had extra features), but I decided that based on our good experience with them, it was the way to go.
I’m with you on glass panels with capacitive switches: so science-fictional!
This “membrane” is a thin plastic sheet carrying the legends atop tab-and-post actuators molded into the heavy red plastic trough (*) supporting the PCBs. Pressing the switches requires pushing far enough to bend the tab and depress the switch button: far more motion than a “touch” switch should require.
(*) AFAICT, the original design had red LEDs behind red plastic. They just changed the mold to add holes for then-trendy green LEDs and kept everything else the same.