Kimball butt springs

[Todd & Kim Mapes]

I recently serviced a Kimball vertical, model 4236, serial B43898, which
belongs to a piano teacher.  She complained about sluggish keys and upon
closer examination, I discovered that several of the butt springs (Pratt
& Read action) had broken off.  My question is twofold:

1.  What would cause the butt springs to break off?  There were a LOT of
springs broken off, and not necessarily all grouped together, but spread
throughout.

2.  Will the Schaff stock springs work as replacements, and if so, which
strength (medium/heavy) is recommended?  Someone recommended using heavy
in the bass and medium in the rest.

Thanks,

Todd L. Mapes
Associate Member