First, crush. That's usually the #1 reason for poor efficiency. - I have my LHBS do the crush for me.
Secondly, conversion. I suggest an iodine test to see if you're getting conversion. - Hmmm ... I haven't done that. But if it does show that I am not getting full conversion, what do I do about it?
If you have a good crush, and you're getting complete conversion, then you can consider lautering efficiency. - I believe this is where my problem is. How can this be increased?
Water chemistry can cause some problems with conversion (pH issues) so if that is checked off, we can look at the lautering/sparging portion of your technique. - I have not personally checked this. The guys at my LHBS said that my Detroit City water is almost perfect for all grain brewing and that I shouldn't have to do anything to my water.
What's your process? - 1) Pre-heat my tun\cooler 2) Empty the pre-heated water, dump in the gain, add my strike water 3) Stir for 5 minutes 4) After 15 minutes give the mash a gentle stir 5) Let sit for 45 more minutes 6) Vorlauf until clear (I use a piece of aluminum foil on top of the grain to keep from disturbing the bed) and then drain out all the wort 7) Add sparge water and stir 8) Let sit for 15 minutes 9) Vorlauf until clear and then drain wort until pre-boil volume is reached.