Raymond and Toby,
...Nor use (anything containing) water! I usually take some butter(!).I only have Danish butter (mildly salted). I will have to revert to Italian butter, less conductive? LOL
You learn something new every day.
On the 4xx scopes never use IPA as it will take the lettering off the buttons.I was not thinking about IPA but thanks nevertheless, the 485 I got has some discoloration already (nothing big) but good to know.