Wow, those programs sound like a real mess to look at
You might look at some software that may help you. I'm thinking of NCPlot, which is a quite intelligent simulator that may actually help you with renumbering the code in a meaningful way that might make it easier to sort out subroutines and such. I don't have NCPlot myself, but I think it attempts to run through subs in a meaningful fashion that will show you if you've got things in proper order.
If you can get the program renumbered properly then you'd have a lot easier time at the control.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)