mk3 125lc needle setting

[robadob]

Just a quick one.

Ive just got my 125lc mk3 back on the road and want to clean up the carburation a bit and have notiv=ced something that may(or may not) be the cause.
I unscrewed the carb slide and removed it from the carb, undid the screw in the slide to relaese the needle and noticed the needle can move up and and down 1mm either way, is this ok or should there be a spring/something that sits on top of the needle to keep it seated? 

Cant find anything on the exploded diagram either.

Symptoms Im getting is very sketchy carburation at between 5-6k, bike cant keep a steady speed in this region and sometimes cuts out only to refire straight away.
Feels like needle to me.

Any ideas??

[museumman]

it's held down by the grey cable holder bit and two screws, the needle circlip gets sandwiched between the slide and grey cable holder bit and should be tight enough that there's almost no movement in needle.

[robadob]

Yep, grey holder bit is missing, that explains a lot.