[Mike O]

How does one learn to produce constantly increasing lag pressure from startdown through impact? I would love to know.

If you have the book "The Golfing Machine"- look under the section 2-M-2- that's the section that will give you the principles for increasing lag pressure, or creating it, increasing it etc. If you're not creating or maintainging lag pressure currently - is it easy to do? NO. Off plane motion and or off plane loading will surely require you to lose lag pressure before impact otherwise you'd miss the ball- I don't say that to make it sound like you have to be perfect to accomplish it but I say it in that it's easy to try your best using some of the concepts and still not be able to accomplish it. Without video of your swing here, and assuming you've tried on your own and are still having problems, then a good instructor would probably greatly help. I'm assuming you've seen your swing on video to help you determine any issues.