Hi Rod, "affixing machine" = "dispensing machine" On the cover note the gripper tear on the stamp, these were meant to pull the coil forward but apparently something went wrong (perhaps end of roll?) when pulling this stamp and it tore into the stamp.
I am not sure about the time frame for 'window envelopes'. Don
The values of the stamps depends on the supplies and demands. Therefore, the question is how many of the stamps have the plate number or selvage, and how many collectors are collecting them. In general, for inexpensive modern materials, these plate numbers and selvage will only add very little values. However, for some old scarce stamps, the plate numbers and salvage may double the price of the stamps.
Call me strange but I like them. I go out of my way to find them. The great thing about stamps is there are so many different ways to collect them. This just adds another sub class for me to collect. They look cool in a stock book. I say keep the extra on.:)