I have to admit this is a great thread. I too found myself in early training for Hassy ownership as a kid, that is how I learned about take up. I also had a yelling at the first "free labor job" I had with a fashion photographer. At 15 years old, loving photography every day I met a pro who let me come to a fashion shoots and he handed me a Hassy back and said "here kid load this". I did a 50% good job, I did not get the film under the silver pincher clip thingie. Thats was why I got yelled at.
It was a worthy experience to get that barking at... I do not mis load my backs since being able to own one now some decades later. The thing that calmed my 15 year old nerves and convinced me to continue in photography was he had me hold up a blanket so the sexy 25 year old model could change clothes outside. It was a "Religious Experience" for me at 15 to have a 25 year old "woman" stare straight at me and smile while she stripped buck naked and put on outfit after outfit.
So thanks for the question about loading Hassy backs. It Pops Up great memories in my mind as a youth.
Lee