If anyone has difficulty with access, then you should ask The National Register of Archives for advise on access, and possibly to intervene on your behalf, particularly where the archive appears on the NRA Register.
As this collection of Chance papers also includes 19th-century pattern books for stained glass, I would not mind having a look myself, except as as folks remind me, "Location, location, location"..... :lol: :lol:
Regards,
Marcus