This brings up old memories. lol I remember back in the 90's I would ( Snail)mail the Henson people at least 10 times a month asking all kinds of questions, and a lot of the time I got really good replies from them.
Once I got a letter from Pat Nugent after asking her if she knew how I could get started with puppets, voices, and writing and she sent be a book " Muppets and men" , and a reliese fourm giving them permission to look at my work with out asking for money for it.
I didnt mind if i got money for my work or not seeing that it was mostly Muppet related anyway. I sent them some of my work and I get a nice letter from May Head saying that she liked what she read but couldnt use it at this time.
I got fan letters from Kathie Mullen, Steve Whitemire, Frank Oz, and a few owhters I can't name off hand but over 10 years I got probably 25 letters, pictures, referrences anything that might be helpful to whatever I was asking for.
It does take persistance, paitance, and time but it;s worth it if you can get what you're looking for.
Not every one of my letters got a replie but don't be dissapointed It took be 2 tried before i get a reply from Caroll Spinney. I would waite 6 weeks for each reply before writing to the same person again just to give them time to reply.