ok - here is the respective chapter of the reference manual of the 4k. if your interested i guess you better download it from here
http://www.akaipro.com/int/download/om_dload.html there you even see a pic of our beautyful timing correct window. its the file MPC4000ref_E.zip and the relevant info is on page 21 - chapter - Applying timing correction to an already-recorded track
Applying timing correction to an already-recorded track
You can apply timing correction to a track that has already been recorded. Executing this operation will rewrite the timings of the note events.
1. Play back the sequence, and verify the track, measure location, and range of notes (or pads) to which you want to apply timing correction.
2. Move the cursor to the TC field, and press the [WINDOW] key. The Timing Correct popup window will appear.
A TC field
Selects the unit of timing correction.
B Swing field
Specifies the amount of swing.
C Shift timing field
Selects the direction in which the entire sequence will be shifted. If you select EARLIER, the sequence will be shifted toward the beginning. If you select LATER, the sequence will be shifted toward the end. Use the Shift amount field to adjust the amount of shift.
D Shift amount field
Specifies the amount of shift for the entire sequence, in tick units. The maximum value that you can set for this field will be half of the value you specify in the TC field.
E Track field
Selects the track that will be affected.
F Time field
Specifies the start and end locations of the region to which timing correct will be applied, in units of measures/beats/ticks. Timing correct will not affect note data outside this region.
G Notes/Pad field
Specifies the range of note numbers/pad numbers to which timing correct will be applied.
H [F1] key (CLOSE)
Cancels the operation and closes the popup window.
I [F6] key (DO IT)
Executes the timing correct operation.
3. Move the cursor to the Track field, and turn the [JOG] dial to select the track to which you want to apply timing correct. If you select track number 0 (All tracks), all tracks in the sequence will be affected.
4. Move the cursor to the Time field, and specify the region to which timing
correct will be applied.
5. Perform the following operations as appropriate for the type of track.
For a DRUMS type track
Move the cursor to the Pad field, and press the pad to which you want to apply timing correct. The corresponding pad number will be displayed in the field, and will be selected for editing.
For an INST type track
Move the cursor to the Notes field, and on your MIDI keyboard, simultaneously press thehighest and lowest notes of the region that you want to select. The note number at the left of the field will be the lowest note of the range to which timing correct will be applied, and the note number at the right will be the highest note. You can also turn the [JOG] dial to change the settings of the Notes field.
6. Press the [PLAY] key to play back the sequence.
You will be able to audition the sequence with the timing correct settings applied.
Note: While auditioning, timing correct will be applied to the entire sequence, regardless of the settings of the Time field.
7. Adjust the settings of the TC field or Swing field to modify how timing correct is applied. When you are satisfied with your adjustments, press the [STOP] key to stop the sequence.
8. To execute timing correct, press the [F6] key (DO IT).
When the note events have been rewritten, the popup window will close.
Note: You can also execute the Timing Correct operation from the Sequence Edit page or Step Edit page.
You can return to the previous state by pressing the [UNDO SEQ] key immediately after executing
Timing Correct.