The semi-weighted keys on the PA1XPRO actually have metal weights on the inside bottom of each key. This is something not found on the PA80. If you just touch the bottom of any key you will feel this weight. this is what is meant by semi-weighted, not an additonal spring.
I've sold 8 boards so far and have not heard of a single problem with stuck buttons or lights on when they shouldn't have been. Your keyboard might be the exception but not the norm.
George Kaye
Kaye's Music Scene
Reseda, California