G'day all,  With all this discussion on tempo and roll speed, I thought
I would mention a related problem which has occasionally bugged me over
many years.

When I got my first pedal player about 20 years ago, it had an annoying
problem with the wind motor which tended to slow down or stall,
probably because some clever person oiled the slide valves.  Every few
months I had to clean the slides with solvent and re-lubricate them with
graphite and I never quite got rid of the problem until I sold the
piano!

Anyway, for a while, I was blaming this motor problem for very long
rolls stalling but I later noticed it was actually loose turns of paper
tightening up on the take-up spool.  The spool was still turning but
the paper had stopped, quite a separate problem from the stalling
motor.  Much of this had resulted from reducing the paper tension on
play-back to help preserve older rolls, so a compromise was needed.

The type and condition of the paper was a big factor and fortunately
very few of my better big rolls exhibited this "feature".  A friend had
the problem with a favourite roll and actually cut it into two halves!
I wouldn't resort to such a drastic measure but often in the past, roll
manufacturers must have had to decide on a long piece whether to
increase the paper length, reduce the paper speed or split it into two
or more.  I'm sure they got it wrong occasionally.

Cheers,

Darrell Clarke
Clarke's Corner, Adelaide
South Australia