And wifes love keycaps in the dishwasher.
So I wanted to try another alternative ... Ultrasound cleaning!
Got this top quality China ultrasound cleaner off eBay for a little more than 50€ delivered. It's a 2l capacity device, should be enough for a couple of caps and the device is small enough to store it somewhere.
Then I also got this really messed up Cherry G80 with nice 1.25u bottom row but totally wrecked keycaps. Thought I'd put them into the Ultrasound cleaner as a first test. Here's the first result after 5min of treatment:
Before:

No further treatment, just threw them into this device:

Result after 5min of treatment:

Now tell me that doesn't look promising!
Put them in for another 10 minutes to see if I can make those pencil marks disappear altogether.