try taking the die apart and using some fine emery cloth on the collet... even between the fingers of it... then as fuj said apply a light film of lube on the inside of the cone... it will make a difference.. another thing that you dont want to do is run the ram up pushing the collet up in the die without a case in it... it can cause the collet to stick up inside the die.... i use several different types of dies to set neck tension... forster , whidden , redding and if lee made the collet die for all the different carts i load for i would use the lcd in all of them along with a redding body die... my .02 cents worth....
The first one I got was for my Hornet when Lee first came out with them and it worked perfect. After the first one I got one for the 223 and fought it and fought it so I pitched it in the drawer and went back to the Redding bushing dies I already had. One day subconsciously the light bulb went on when I thought about that 223 collet die. Yep! Big time operator error on my part and I had already been using one. And on the Hornet I had been using a Wilson neck only bushing die with an arbor press. The Lee collet die will perform if you take a little time to figure them out. gman's post touched on a lot of good points.