No problem fellas.  My MK1 was a bit ropey, then I saw another using nice coach bolts and proper slotted holes at the adjustable end.
I have another method that the bowyer I'm working under uses.  2 pieces of wood about 2" wide, 3-4" long with a V cut up the middle of each and strips of sanding belt fixed long their length to cover and pushed into the 'V'.  the pieces of wood are then joined with a couple of hinges so when you look at them end on, there's a square hole.  shafts can be spun with the jig lightly gripped on the shaft, then run back and forth working more where more wood has to be removed.