Security keys on 95 Aurora 206,000 miles

The key on my 95 Aurora will often trigger the security light to come on and not start, which means waiting several minutes before you can retry. If I carefully push the key in firmly as I attempt to crank the engine, it will usually start, but not always. I have cleaned the key as instructed in the owner's manual when this happens, but it doesn't seem to help. Is there a contact inside the ignition switch that also needs to be cleaned? If so, what would work best? I was thinking of using TV tuner cleaner (used on old style rotating tuner TVs), but was afraid it might do damage or remove lubricants from the tumblers.