I was out riding the countryside yesterday (it seemed OK at about 90F until you stopped for something ) and noticed that my horn button didn't always make contact and it didn't seem to be steering related.
When I got home I pulled the button off and must have emptied 1/8 of a can of Electrical Contact Cleaner into the housing while swishing it around as much as possible and pushing the button in a bunch. Seems to be working OK, now. That CRC contact cleaner (I got it at NAPA) is pretty good stuff!