Pool light only comes on if I tap the lens

Hi, I am new to the sight, my pool light will come on by the switch, but not all the time. If it does not come on by the switch I have to go out and hit the lens once with my hand and it comes on and stays on. I put a new bulb in last year and the other day I soldered the all the connections in the junction box outside the pool, oh yea I have a in ground pool with a Hayward light system 12 volt.

Is it possible that the bulb connector is bad, I tightened the outside screw, that did not work, I just find it strange that by hitting the lens makes it come on, nothing is loose, the fixture is tight and perfectly sealed.

If anyone has any suggestions I would greatly appreciate it.

Thanks,
Joe from Florida