This test can help you determine where to first focus your energy when the Lisa needs repair related to a vacuum related error code: A-31, A-32, A-33 or A-34.
Remove everything from the chamber, including the rack and check for any debris.  On the touchscreen, press the M in the lower right corner to get to the menu.  Use the up or down arrows to navigate to SERVICE and press the icon in the lower left corner.  Use the arrows to navigate to VACUUM TEST and press the icon in the lower left corner.  Press the large icon that appears to start the vacuum test.
The vacuum pump should start running immediately and the pressure on the display should move in a negative direction.  Once pressure reaches -12.3 psi, the vacuum pump should shut off.  If this happens in less than 3 minutes, your problem is most likely a leak, and once the vacuum pump shuts off, you can confirm this because the pressure will start to rise in a positive direction (save time and abort the test by pressing and holding the stop button in lower right).  In this case, your leak would most likely be at the door seal or one of the solenoid valves.  Clean and/or replace the door seal and activate the solenoid valves in the diagnostic menu to confirm you can hear them clicking, cleaning and/or replacing them if necessary.
If the pressure doesn’t reach -12.3 psi in 3 minutes, the problem is most likely with the vacuum pump.  Abort the test and check the vacuum pump.  Rebuilding the vacuum pump will often correct this problem.