@vwestlife Could it have been that the early short tapes were thicker, and needed some sort of careful spooling lest the looseness of the tape cause the tape not fit onto its uptake spool, and later tapes were thicker and could be safely spooled in potentially-faster-but-less-steady ways? I suspect if this was the case, ordinary playback would necessaarily have used the carefully controlled steady spooling both ways, but fast forward/rewind might run faster if the switch is in the "T80~" position.