Are you having problems with both the LK and LM positions consistently printing, or did you mean "LK" when you typed "LM" and are only having problems with the LK position?
After reviewing your order history, I see you have been using ConeColor Pro inks in your 3880 printer since the end of 2010 (with old model refill carts), and just recently bought the new model refill carts. Do you have all the new model refill carts installed, or are you still using some or all of the bigger/old model refill carts? If you are using the new model refill carts- please check the carts to make sure 1. the exit chambers are at lest 1/2 full for proper ink flow and 2. there is a small air gap on the top of all carts for proper pressurization and ink flow.
Please let me know so I can help you resolve this and get back to happily printing~ Dana