Newbie with problems printing the demo prints

Hi, I've recently bought a Finder. Ive so far limited myself to printing the items in the memory. I've successfully printed several of the small cubes which have rafts, and also I've printed a model railway item from a download which printed right once I had placed a raft under it. The problem i have is when I try to print something that does not have a raft, eg the phone stand holder. I have noticed the pla peels up from the base when it is initially put down, in addition once the model has printed for about 30 minutes on this and started to infill then the stand peels up at all sides and along the lengths and the print is wasted. Do I have to always print with a raft? I've levelled the base several times. I've also used alcohol wipes on the board followed tips I saw on other sites on how to help adhesion. I've used glue but this made no difference at all. Help!