Hi!
I am sorry, JK, but you make it sound like tapes from Mellotron Archives don't work in the old frames. This is not the case.
We've sold hundreds and hundreds of tapes for old tape frames since 1990 and the customers have been pleased with the option to shorten the tapes to ca 7 seconds (like most of the old frames) or put in a bit more tape (like Änglagård for instance).
Like I said, in the new frames you can put in even more tape length.
Making tapes for old frames was the main thing when David Kean started out in 1990, making tapes for old and neglected machines, resurrecting them when nobody else was doing this.
Best
Markus