I've played with a home made board and I've had the same issue, I just had to take it down and throw it out.

I personally think ouija boards are mediums for communication istead of portals. They just attract spirits into it due to the powerful energy it creates. I sugest opening the Light where spirits are able to cross over. If she refuses. I suggest making an energy vortex that forces and sucks her into it.

Yes they are a media for communication.  Sometimes we might want to consider - from where?  

There are many spheres in the afterlife.  And most uneducated and untrustworthy of these spheres is the one closest to the earth plane.  Any board will open the portal and attract such entities.  So what do you gain from this level of spirit communication?

There are many well tested, tried and true methods to reach to higher spheres of communication.  The higher our own intent (spirituality) the higher the entity willing and able to communicate.  But if you continue to fool around at this level of communication, the caring and loving will back off and allow you the experience.

I find most ouija boards help you communicate with the dead, as in those spirits lingering in the etheric plane before crossing over. I think you'll attract negative spirits because the wavelength(?) of your thoughts correspond to the negative entities and therefore attract them

But I also heard some people are able to reach higher entities through the ouija board. Is it though positive thinking and intention alone or is there something else to it?

No one has ever reached the higher entities through the ouija board.  But many people are unwilling to realize this because of the law of attraction.  When they open and invite all and sundry that is the attitude and what they get.  

Unfortunately the loving, caring and trustworthy can not get through this kind of negativity.  When connecting with this energy there is a warm glow that accompanies any and all spirit communion.  They feel they are higher than they are in spirituality.  

And just like astral travel, it may sustain and even energize them for a period.  But watch out for when it wears off, they are so totally depleted because it is an exercise in using our own physical exercise that creates this glow.