Hi Roberto,
you can order a 2x3x4 together with a DIY kit here
http://www.hknowstore.com/locale/en-US/ ... 1a57dbd014hknowstore had offered the kit itself for $1 in the past.
Calvin might still send you one, at least if you are a customer.
Despite all of my criticism that mf8 lets its customers suffer from a decision made because of "different culture" (quote from Calvin), I highly recommend doing this "repair". A few posts above you can see that the operation is not so easy.

I did it avoiding a full disassembly just changing one edge at a time.
I had got a second 2x3x4 for
free from Calvin (Manager at hknowstore).
I swapped three sets of split edges from the first into the second and got a wonderfully turning FF 2x3x4.
I plugged the left over three unsplit edges back to the first. This makes a shapeshifting 2x2x3, because you cannot do any inner layer 2x3 turns.
EDIT:
Doug Roth wrote:
...I don't think so. AtomnicCubeLube said "A fully functional 2x3x4 WITH the modification". That means it is fully functional, and has another modification.
Plus, you don't need a modification to make this puzzle fully functional- you can just buy it.
-Doug
The mf8 2x3x4 was always labelled as "fully functional". When the bandaging turned out to be a problem (at least for western twisty puzzlers

), they changed the name immediately to "mf8 Full Function 2x3x4 Cube Black Body with
bandaged mechanism". You can buy it e.g. at hknowstore with or without the repair kit. You cannot buy it as FF 2x3x4 as you
expect it. It will come
bandaged. If you are interested in the details you can read backwards in this thread. AtomicCubeLube wrote
THE modification. What else could he possibly mean?
You can check out the posts of Melysa to find that it is not super easy to get a
truly fully functional 2x3x4.