I have seen many cracks in plates.  Some plates have small cracks that
are not to be seen until you clean off the old gold paint.  Then you
will notice that they were filled with putty and painted over at the
factory.  We just ignore it and restore the piano.

Bechstein plates usually crack in the top end of the bass tuning pin
areas.  It is a standard Bechstein trait.  Most of them have a crack
at this point and have had for the last 70+ years.  Ignore it.

Usually any crack in a non-load-bearing place can be hidden and
ignored, as long as you make sure the boards under it (say, the pin
plank or timbers) are flat.  If they are loose and flexing under the
plate then, over time, the crack will become a break.

If the crack is in a load-bearing place you have a choice: either
junk the piano, have a new plate cast, or weld or braze the old plate.
Having a new one cast is very expensive, if it's even possible.  If
you weld or braze then expect the distinct possibility of it breaking
again, right next to the weld, at which time you will probably junk the
piano.  But it is possible the piano will stay welded for many years
to come.

In a church I had a fairly new Baldwin studio piano that had the
problem of the dampers not lifting with the pedal.  When I looked at
it I found the plate strut between treble and middle sections was bowed
out and was pressing on the dampers such that the treble end of the
damper lift rail could not move.  The nose bolt had pulled out of the
timber in the back and was totally loose.

Horrified, I quickly took all pressure off the strings in the treble
and middle sections, pulled the action and discovered that the plate
was cracked parallel to the nose bolt, which was nothing more than
a large flat head wood screw that had stripped out of the wood beam.

Since the crack was only 80% through the cast iron, I went and got
a T-nut and large machine screw.  I drilled through the timber in the
back and put in the T-nut, threaded in the machine screw, and began
slowly pulling down the plate.  I took about an hour to slowly pull
down the plate to what looked like the original level.

I retuned the strings and reassembled the piano.  It has been going
now for five years and the church has not had any more trouble with it.
Whew!  That was luck!

I also had an old Melville Clark upright that came through the shop for
refurbishing.  The bottom of the plate, which normally lies flat
against the bottom of the soundboard, was bowed up from the soundboard
in the middle about six inches.  I noticed that the bolts down there
had stripped out from the rotten blocks at the bottom of the timbers.

Horrified, I lowered all tension on the strings throughout the piano,
turned the piano onto its side and, after replacing blocks between
timbers, put in T-nuts again and long bolts.  I used my wooden
hand screw clamps and put them in place to pull the curve out of the
cast iron.

Over about two weeks, I pulled down the plate by doing one small turn
each morning and one each evening.  When it was pulled down enough
I put in the machine screws and continued until all was touching the
soundboard at that edge.  I then retuned the piano and it has been fine
thereafter.

The amazing thing was there was not a crack to be found in that plate
and I had no idea that cast iron could bend and bend back like that
without breaking.

D. L. Bullock    Piano World    St. Louis