brake light problem

OK I got a 90 xj and I keep having problems with the brake light switch. After trying a few switchs I have pretty much ruled out the switch as the problem. I will be driving and all of the sudden I will no brake lights. If I push up on the switch they will come back on. The switch itself is tight as I can make it on the bushing (if thats what you call it) on the brake pedel. Any suggestions and or upgrades that you can think of is appreciated. I'm sure my luck is running out w/ the local police.