Mysterious blocking notes

[Maxpiano@aol.com]

Aaron -

Have you checked the clearance between the hammer and backcheck to see if the
backcheck catches some portion of the hammer as it starts (particularly on a
hard blow, where action parts flex a bit)?  I had one case where an
intermittent blocking was due to the backcheck snagging the staple of an
overly large hammer.  Running up the capstan (blow distance needed shortening
anyway) solved the problem.

I have also experienced backchecks grazing neighboring hammers and giving a
similar resistance.

Hope you find the cause and correction.

Bill Maxim, RPT