The Dritz cone thread holder is all plastic and after its used for a while, the thread mast starts to bend over. Its better to find one that's all metal. Here are some links to metal ones.
http://www.sewingmachinesplus.com/cone-thread-guide.php
http://www.superiorthreads.com/shop/...tand/products/
http://www.purplemoosedesigns.com/thread.htm