Bintelli

When braking, the tail light isn’t illuminating brighter to indicate I’m braking. Wanted to change the bulb to see if that would fix the problem. No idea how to get to it or how to remove the tail light lens to get to it. Seems like a lot of dismantling to get to but still wasn’t able to free it. Any suggestions or solutions?

Would the intake manifold with aging cracks in the elbow cause loss of power,and cause it spit an sputter when you try giving it half or full throttle?