I suppose that you are sanding the kapton to stick better the models on the bed and I know that it ,sometimes works but not for everyone.
I prefer a different way that works well : using a 2mm glass on the bed and low cost hairspray or a coktail made with abs and aceton. The second one stick sor much that you must wait until the model is cold to take off the model from the bed.
I going to traduct a beginner's help thread that I made for solidoodles's beginners and post it . I will give some useful tips and also some upgrades for the solidoodle's printer