I rebuilt a Steck during winter 2009-2010 as a first project.
Before I got started I pondered the question of whether the 80 years
since the pianola was built had brought about big improvements in
gluing technology.  After all, surely a glue boiled down from old
carcasses had to have been improved upon.

Well, to cut a long story short, I bought a pound of good quality
hide glue, bought a mini deep fat fryer for very little money and
after playing around with the thermostat for a while got a nice little
hot glue setup.  And, I suppose like thousands before me, I discovered
that hot glue has just about the perfect combination of qualities to
glue natural materials like the wood, cotton, leather and wool of which
a pianola is built.  In fact I was amazed by its strength and 'grab',
something I hadn't really expected.

So RTV is not for me.  I'd rather use a glue that is easy to work with,
forgiving, removable, sandable, cheap and even smells right.  During
the restoration I learned the hard way that alternatives like PVA glue
are incredibly difficult to remove; I ended up milling the stuff off
motor pneumatics put there by a previous 'restorer'.

So my advice would be to try traditional hot glue.  You'll probably
end up wondering why you even bothered to think about an alternative!

Mike Wilkinson
West Sussex, UK