There has recently been some discussions of repairing a broken or cracked 
record.  Everyone seems to have their own pet solution to the problem of making 
the record play again, some come close, but none provides a fully restored result.

For some time, I have been intending to post an example of using CEDAR 
processes to restore a broken record and here it is.

This one is seriously cracked, but the process for a fully broken disc is 
essentially the same... get it into a playable condition and use computerized 
de-click and de-thump processes.

The source disc is a 10" American Record Corporation No. E 587 issued around
1930, for theater use.

Love, You Funny Thing! - Imperial Dance Orchestra

See label photo here:

It was recorded at 33-1/3 rpm, transcription style inside start, with the same
tune on each side.  The disc has a large 1/2 moon crack in it with one end
still intact, but hold it up to light and you can see light through the
separated end!

See surface crack here:

See entire crack here:

Reasoning was, they were played by the projectionist to synchronize with
showing of a silent film.  Being shellac discs, and with the heavy weight of
the pickups and steel needles, the discs wore out very fast.  As one side
became noisy, the projectionist would order a new disc and start using the
remaining good side.

One pass used CEDAR de-clickle to remove the leading impulse clicks.
The remaining thumps were removed using CEDAR de-thump installed on SADiE 5

The two audio files can be lined up to see there is no timeline discontinuity
as there would otherwise be with conventional physical editing.

Here is the de-clicked file prior to de-thump being done:-

Here is the finished de-thumped file:-

... Graham Newton

Audio Restoration by Graham Newton,
World class professional services applied to tape or phonograph records for
consumers and re-releases, featuring CEDAR's CAMBRIDGE processes.