Would agree with Larry on this ,as a while ago i was able to purchase a ex Bedford dealers set of fiche's which were of a large size 10 x 8 inch , took them to the local library only to find that the machines there would not read them ,as they would not fit .
Then by a stroke of luck found the correct reader on ebay , which was also an ex dealers machine , must have been specially made for Bedfords as have never come across fiches of that size again , this has given me a fantastic resource of info, as the fiches are of every Bedford made from the 60s onwards.
Out of interest is it a flatbed reader ?, as also have a set of Leyland fiches which are of a size 6x4 inch , but no reader .