This is a very broad question. I believe that the alignment of a M15a is pretty straight forward - if you know how to align a tape machine in general? If you don't, did you google for it? It is a pretty laborious procedure and I wouldn't be surprised if someone explained it somewhere already. It is basically a universal procedure which is not specific for only one machine type, once you know one, you basically know them all. There might be small differences, for example whether the repro eq has one or two adjustable frequencies. The M15a might have two if I remember right.
Michael