Hello MMD.  I have been rebuilding the little valve chest in an Aeolian
player that sits on the top deck and contains the bass and treble
primary theme valves.  These valves have screw-in top valve plate and
stem guide combined in the same unit and are made of brass.  I believe
these two valves are the only ones in the entire action that use this
type of valve plate.  I thought that this arrangement would made the
setting up of the valve travel very straightforward and so it may, if
only I can get the valves plates screwed back in.  They unscrewed very
reluctantly but I did get them out without damage.  But getting them
back in is proving nigh on impossible, and I am worried about breaking
them.

I have made up a tool which is essentially a large screwdriver with
a notch in the middle of the blade so that the blade doesn't interfere
with the valve stem.  Even so the necessary torque to get the valve
plates even halfway back in is getting ridiculous, and I'm not prepared
to go any further.  I tried a bit of plumber's Teflon tape but that
didn't help.  I realize that this tape is really intended for situations
where the male and female threads are not very tight.

I tried putting a valve plate in the freezer for an hour or so; this
helped a little but there isn't much heat capacity in a small bit of
brass and it warms up fairly quickly.  I don't want to put the whole
valve chest in the freezer because I've just treated it to a lot of
fresh glue and burnt shellac and I don't think those materials would
appreciate the experience.

Now I'm wondering what the specifications of the thread itself are.
Does anybody know?  I may be able to get hold of the appropriate tap
and ease the thread in the wood very slightly.  Does anybody know why
Aeolian used these valve plates for theme valves, but nowhere else?

In Anticipation,
John Phillips in Hobart, Tasmania