Jack,  The shut-off pin is very often found broken off, just as you
describe.  In fact, on the six machines setting around here, I think
only one is original.  It appears to me that there were two styles:
the earlier machines had a rectangular cross-section (like a square
(cut) nail) and tapered out from the shaft (also like a square nail),
while later models may have simply a round pin.

To remove the pin, you'll need to press it out from behind: the hole
goes all the way through the shaft and it's just force-fitted into
place.  (By "behind", I mean opposite the groove in the shaft.)  If
you don't have appropriate tools to press it out, it's possible to use
a clamp or pliers and a smaller diameter punch, but take great care to
protect the shaft surfaces.  An alternative is to drive the pin out
from behind with a punch and hammer, but you _must_ support the shaft
securely, otherwise you'll end up with a bent shaft or a broken
casting.

To make a new shaft of the tapered variety, I've successfully tried
two methods: First, I've found that some cut tacks are about the right
size.  The pin should taper to about 1/8 inch at its widest, and stick
out approximately 1/4 inch from the shaft.  Otherwise, it is easy to
make a tapered pin.  Take a plain nail that just barely fits into the
hole, and hammer it on one end until it tapers out satisfactorily.

Either way, I find it easiest to cut it overly long, put it in place,
and then remove it and trim the length on both ends.  I file the ends
mostly square.  A little longer (or even shorter) than 1/4 inch pro-
truding seems to do no harm.  Make sure that you put it in the correct
direction -- it should stick out from the grooved side of the shaft.
(Yes, I've seen one installed backwards, and no, it didn't work.)

To answer your second question about loose pins, I usually just
straighten the pin and apply a drop of Super Glue (cyanoacrylate)
to the base.  It seems to soak into the wood to strengthen what's
left, and can be repeated if there's a noticeable gap.  I've done this
to several rollers in my own collection, and had no problems

If you haven't found my web site yet, for much information on
Roller Organs, including Roller titles, and a Buy/Sell/Trade page,
take a look at  http://www.bright.net/~allmax/index.htm

Todd Augsburger
http://www.bright.net/~allmax/index.htm