Woka,
Not sure – I have an S7, which has a different (and much better designed) construction, but it looks as if someone has chopped off the spigot. If you remove the cross-slide you wil probably find that the remains of the spigot can be removed. Then you should be able to make a replacement which has the upstanding part a close sliding fit in the hole in the topslide.
Even with your mutilated set-up, it should be perfectly possible to fix the topslide firmly in place with the two locking bolts to allow you to machine a spigot.
The more I look at it, the more I find it hard to imagine what the designer was thinking of the day he designed that POS system on the ML7. If funds permit, one day you should consider replacing it with an S7 cross slide/topslide.
(ducks below parapet)
David
Edited By David Littlewood on 03/10/2012 22:28:44