Chosen Solution
My back cover screws seem to be cross threaded and screw in about 60% of the way. I do not want to use any more force which may strip the head.
If the screw is damaged, replace it. If the threads that the screw turns into are damaged, I would put a small amount of silicone sealant or other type adhesive glue of your choice on the screw, then thread push into place. When dry it should hold sufficiently and wont be very hard to turn out if the need should arise.
The above method would not work in my situation but thanks for your response. The screw is fine but the aluminum case thread was cross threaded. Because of the change in angle of the screw it only went in 60% of the way. I would not go any further without stripping the head. I used a Dremel cutoff blade and cut a slit in the screw . This acted to cut into the aluminum hole and I got 3 additional turns but still insufficient. Next I cut the screw in half to shorten it with Dremel. I also chamfered the tip to make a lead in and dress the threads. This worked great. I will have to be careful when I remove and insert the next time.
