misfiring jack

[Roger Jolly]

Hi John,
         If the wippen centre pins are starting to cease up due to
verdigris, this could account for it. If the keybushing are badly cupped
same result.
This piano was probably too light from the get go. So weighting could
give a major improvement. Measure the DW and UW to get some indication
of where to place the lead. 48gms DW usually works well on these small
pianos. Remember to have the damper pedal depressed when measuring.
If you weight off, fix the key bushing first.

A fast and nasty, temporary fix for no friction re key pins. Take an awl
and spring the balance rail pin forward, and out of the worn cup, turn
the front rail guide pin for only .005" side play. this will stop the
key from flopping all over the place, and make the instrument much more
playable.  A lot of energy can get wasted when the key is wobbling
about. Instead of driving it straight back.

Hope this ives you some thing to try.
roger



H. Pengelly wrote:
> 
> Dear list, I recently tuned a Homer upright spinet that had a few
> miss-hitting keys. Upon closer inspection I noticed that the jack wasn't
> slipping back under the hammer butt. The key bushings are fine and the lost
> motion is set properly and the problem persists. Incidentally the action is
> miniature and the keys from the balance pin bushing are cut at a slope to
> clear under the wippens. It appears to me that the back of the keys are too
> light and sit up too high thus preventing the jack to return. If you press
> lightly down on the back of the key then the jack goes back. There are no
> weights in the keys and they are quite front heavy. When the soft pedal is
> depressed the problem is worse. The front of the keys dip as if the bridle
> tapes were too tight but they aren't. The weight of the action seems too
> light  to stop the keys from rising up at the back. In my 16 years of tuning
> this is a first for me,I know I've been lucky, and it has me perplexed. I
> could probably fix it by adding weights to the keys but it originally worked
> ok so what are your thoughts? Much appreciated
> John Pengelly