Thanks AV8 for your helpful and specific advice. I now think I have it working pretty well. Just played a game and had quite a few bell shots and maybe one of them came back STDM. I call that fair enough. No changes to play field posts or rubber.
I set the pitch to exactly 7 degrees. To get it perfect I machined a wood block to an exact 7 degree wedge. I then used a precision torpedo level on the wedge. Turns out 7 degrees corresponds to the Stern bubble level reading with the bubble just touching the top line.
I set the side to side level at 1/32 of a degree tilted to the left but test playing that was not to my liking. I could tell from the game play that the playfield was favoring the left side. So back to the drawing board I leveled it side to side and then added 1/6 turn out to each right leg thus making it barely tilted to the left. This moved the bubble on my torpedo about the width of the indicator line - not much.
As far as leveling the game left to right in general, I start by measuring the botton of the cabinet front and rear and get those perfectly level. Then I check the playfield indexing the bottom of the mini-playfield window. Turns out the playfield is not perfect to the cabinet as I originally thought. It is off about 1/16 of a degree. I then adjust both front and rear legs on one side the same amount by counting rotations until I get the playfield to the level I want.
I know some of you said you check level multiple places on the playfield, but I sure do not see any way to do that accurately. I can't see any way to index the level square to the playfield which means I cannot take an accurate measurement any where other than the bottom edge of the mini window. Please feel free to enlighten me if there is some other spot you can measure and index.
Just to confirm my theory, I tried moving the level slightly off the index to see how it effects accuracy - and it is significant. Moving the level (which is 9" long) just 1/8" off the line at one end, changes the measurement by about one index line in my level. So if you cannot index the level perfectly, you cannot take a usable / accurate measurement. I still think that those who are not having STDM problems lucked into a good level setting which is in reality not perfectly level.
Sorry if I wrote a book on this, but I thought it may help others who are frustrated with the STDM drains.