I used a diamond file to remove any minor high spots (took only a couple of passes) then used a ceramic stone to polish the contact surface. They say not to do this because the factory trigger is basiclly pressed powder with a hardened surface. Now I may have just got lucky but the trigger has functioned flawlessly ever since I polished it and the sear. For the sear I used an Arkansas hard stone. I got the trigger to about 2.5 lb.

I don't know if my efforts did any good at all, it may have been the spring change, but the trigger feels good. For reliable results, Rifle Basix and Timney both sell replacement triggers that are capable of producing lighter trigger than a polished factory trigger.