The Lighting Controller

Can anyone suggest a good cleaner for DMX contacts.
Often when I set up I have problems getting all devices to work.
Usually a drop of Isopro does the trick but it happens too often.
Have checked out all cables by swapping but it often comes down to one of two connectors either on leads or fittings

do you use a terminator in the last fixture? if u have problems with no comunication in some fixtures this would be a great option... it works for me a lot... (in a permanent installation)