Thank you, Levente,  for this valuable hint :-)

This paved the road to sucess!

The following process now has worked for me (adapted from Eliot's instructions)

1) Download http://files.squeak.org/6.0alpha/Squeak6.0alpha-17086-32bit/

2) Verify the last update map loaded by opening a Workspace. Then evaluate
       MCMcmUpdater default lastUpdateMap
    This gives me
    'http://source.squeak.org/trunk'->402

3) Open a Monticello Browser and and click on
'http://source.squeak.org/trunk'; click 'Open'

4) Locate the second to last entry called 'update' and there
'update-eem.403.mcm' (see attachment); click on 'Load'

5) Load (or merge) update-eem.406.mcm.

6) Save your image.

7) Locate the Kernel package and click on 'Kernel-eem.1078'; "Load"

8) Save your image.

9) Choose 'Update' from the Squeak menu.


RESULT
------------

As of today this got me to version #17138

--Hannes