I have a bunch of RN4075 atomizers from Heaven's Gifts. They work great on my prodigy with the 901 adapter. However, tolerance differences between manufacturer's being what they are, they all fit a bit wobbly. That is, I cannot screw them down till they seat firmly or I will lose contact. Hence, I must periodically make adjustments. I can live with it, sure, but if someone has any tips as to how to make a firm contact between the atomizer and adapter I would appreciate it.