I have been eyeballing the brushed motor's cooling vents and how some heat sinks cover one of them. I put 1 and a half of another before realizing I left one hole open and the other covered. Not good?
Also I picked up one of these, the top just covers both vents.and am going to open up those areas. A swath with a 1/2 " end mill about 1/4" deep will do nicely I think.