Yesterday my new Audio Technica 440mla arrived at my door. I had taken off my old AT cart off my Thorens TD-160 in anticipation of the new carts arrival. I didn't have an issues with my old cart, and didn't install it myself. I figured this time around I ought to because it didn't seem like it would be too difficult. Well my cart is still not installed. I have a washer to hold the screw to the headshell and from there I am going into the tonearm. I managed to get the cart on but once I tried to connect the needle it immediatly fell off. I don't understand what I am doing wrong. The connection on the tonearm doesn't seem stripped....the headshell just will no stay on. Any suggestions?