I only have one punched ribbon to test out the composition casting on my Monotype, and this ribbon is wanting in more than one way.
For one, it was my first (and I hope only) attempt at punching a ribbon on the Monotype keyboard. About a quarter of the ribbon is kill lines (when you make a punching mistake on the keyboard, there is no backspace or delete, so the best you can do is kill the entire line and start over). Although the caster will not cast any type for such lines, it still cycles through the ribbon at the same speed as if it were casting, and while it is doing this the mould is still being chilled by its cooling water supply. As a result, when the end of the killed line is reached and the machine starts casting again, there is a good chance of miscast types or even a nozzle freeze (and nothing casting) until the mould warms up again.
The other problem is that I was using this ribbon while I was testing and adjusting the air tower on my caster, so it has a large collection of torn sprocket holes and other tears as well.
I spent some time in the past few days trying to repair the ribbon. I cut out the kill lines and spliced the cut ends together, repaired tears with tissue, and used some of the cut-out kill lines as a supply of sprocket-hole repair strips.
The end result is a ribbon that is entire, but because of the thickness of the splices and patches, will not run smoothly through the air tower because it is set for minimal lift of the air bar. When the bar is raised, there is only enough clearance beneath it for 2 or 3 thicknesses of paper, and a lap joint is a minimum of two thicknesses, plus any roughness and glue thickness.
To enable this ribbon to be read, I have readjusted my air tower to provide more clearance for rough or damaged ribbons. Details on this procedure in another post.