Dear Colleagues, I need some suggestions from you about AFM. Our Nanoscope III AFM has a problem since December. After the "engage" button is clicked, the tip moves down infinitely engages until it breaks. We changed different tips, used both J and D scanners, two different optical heads, two different tip holders, but the engaging problem is always there. We have contact with the AFM manufacturer and they were thinking of the problem of Z-Board in the controller. However, after we installed a new Z-Board from them, the problem still keeps the same. Do you have any suggestions on how to fix such a problem? BTW, I remember there is an AFM forum on the internet, but can not find it again. Do you know about it? Thank you so much for your help, Hongjun