Here's a fixed-up version of this classic manual (correcting the scanning errors from p. 71 onward found in the original): https://github.com/PDP-10/muddle/blob/master/doc/MDL_Program...

Other significant MDL manuals (including 2 similarly fixed-up versions) can be found here: https://github.com/PDP-10/muddle/tree/master/doc

https://archive.org/details/ADA070930/ - A somewhat better scan of the same text.