Hey Peter,
Is this something you have to do frequently? I ask because I don't normally have to perform contact cleaning in my studio unless I actually hear some crackling, which is very rare. Of course, the studio is an atmospherically controlled environment that generally varies from 60 - 75 degrees F and 20 - 60% humidity. However, some of my clients often have problems repeatedly in substations and generation facilities that are not temperature and humidity controlled, meaning that they're not both heated in winter or air conditioned in summer. Winter causes condensation problems and summer offers high humidity, bot causes of corrosion. I have a friend who has this problem in his garage studio because it is only heated when he has a session and does not have A/C for the summer.