[CAUT] Renner back action

[Jon Page]

Typically, the S&S key lifts the underlever to ~1 3/4" above the keybed.
It is simple to verify this by depressing the key and measuring the
elevation of the key end felt.  Or measure the height of the felt at rest
and add your key dip.  S&S key end felt is usually 1 3/8" above the key
bed at rest, add 3/8" dip and you get 1 3/4".  Generally speaking.

Place your ruler alongside the underlever and lift it to 1 3/4" and notice
the angle of the underlever to the keybed. If it is parallel, that's great,
if the end of the underlever is 1/8" below being parallel, you can live
with that; 1/4" below and you have a friction problem.

Lift the underlever until it is parallel, measure that distance from the bed.
Subtract 1 3/4" (or whatever your situation might be) and that is how 
far off you are.

You can't simply remove the support blocks and drill a new hole 1/4" lower and
reinstall. If you did, the front end of the lever would rotate upwards since it
will pivot at the top flange center being suspended by the damper wire.
A full timing adjustment is needed.
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Regards,

Jon Page