Gear shift won't move all time sometimes no problem. on 1997 Chevrolet 1500 Pickup

I can put it in gear no problem, then I can park it start truck back & it won't move I can keep messing with it & brake pedal then it we will move fine can do it over over works great then turn it off try again may or may not work??

1 answer
poss pwr issue to shift lock solenoid.start by cking brake light switch