Hi

Ok, using the *standard* old version of Marlin:

1) Do a manual adjust on the Z and get it within about 0.1 to 0.3 mm above the glass. This is all by adjusting the Z end stop.

2) Run the bed level on a heated machine (heated bed hot and hot end hot) Use a piece of paper, do it from the LCD

3) Do a G29 command from your computer. Record the numbers it spits back

4) Wait a bit and repeat the bed level, repeat the G29. The numbers should be the same, if not start digging into what's wrong with the printer

5) If the numbers repeat, save them using the "store memory" function under the "control" menu

At this point, the only thing you need to adjust for is the thickness of your paper. Unless you have a very unusual piece of paper, that will be in the -0.05 to -0.25 mm range. It has nothing to do with the data from the G29 it only relates to your paper. Make sure that your G code has the proper default info in it to run the bed level stuff. All of the details are in the Pegasus 12 instructions.

If you need to dig into the printer, I put up a monster long series of posts about how to do all of that.

Bob