1993 Camry LE 4 Cyl...

the car won't turn over/start sometimes due to a problem when the shifter is in "PARK" position..

I can get the car to start if I "jiggle" the shifter and move the "thumb" release button back and forth a few times...

any thoughts? is there an easy way to try and clean any contact points in the electrical parts/sensors in the shifter assembly or shifter release button?