I am an old-school die-hard player repairman.  I usually do work on
players that have already been done by others.  I will admit that
I rarely work on 88-note players but do work on the coin-operated type
of players.

I have seen pouches sealed over the years with who knows what.  If you
seal the pouches with something that is sticky then I guarantee you
will regret it later.  Somehow dirt and dust seems to collect under the
pouches preventing them from working correctly.

If you use a silicone product then you will most likely have adhesion
problems later.  I suggest thinned rubber or don't thin it but use
rubber cement.  It just works and you cannot ask for anything more.

Don Teach