Jim,  Easing the friction is the first step in restoring repetition.
Then regulation to set the mechanisms adjustments (timing), which
includes the repetition spring.  If the hammers have been replaced,
chances are that they are too heavy for the action and causing the
problem.  New action parts would need to be selected carefully to
optimize the action leverage.  Contact a technician for this.  Ask
if they have the Renner USA Parts Kit for comparison.

I recently sold an 1885 Bechstein grand with all original parts.  They
were fine and new parts would not have been a significant improvement.
Of course, new hammers would have made an improvement in the sound, but
as far as playing, no better.

Check out this web site.  Any action (_any_ action) can be improved
with the application of Dave Stanwood's process.  Follow the link to
the list of installers and see if there is someone in your area.

    http://www.tiac.net/users/stanwood/first.htm

Regards,

Jon Page
Harwich Port, Cape Cod, Mass. (jpage@capecod.net)