Key dip

[Clyde Hollinger]

Friends,

While tuning a 1980 Wurlitzer studio piano today I noticed some of the
bass hammers would damp the strings depending on how they were played.
Letoff was fine, but there was too much keydip, resulting in the
backchecks pushing the hammers into the strings after letoff.

It appears to me that all other specs will be in the correct range if
the keydip is reduced.  Can this be done by shimming up the front rail
of the key frame, if there are no shims to remove from under the balance
rail?  I've never tried this.  I could put card punchings under all the
front felt punchings, I know.  Advice?

Regards, Clyde