Had another prod at it today 
left the shift linkage cover off while I tried moving it on the spline while I gave it a run 
can get 1st and 2nd easy (plus neutral) 

Anything above 2nd seems to be pot luck,
sometimes I get a gear or two, more often not though 
tricky where I am running it around as run out of road pretty quick
have it shifted down to 1st now for sure (I think last time i   Tried it hadn't shifted all the way down to 1st) 
will update when I have figured why o can't seem to reliably get gears after 2nd 

 

There is a linkage adjustment (eccentric screw) that was mentioned pages back.  Possible the "claw" is not centered correctly.  Also as I said earlier it didn't look like the left side shift linkage was in a straight line...  it looked biased to where it might impede upshift...  hard to tell though, could have just been parallax distortion of picture taken at an angle.

thanks with the cover off am able to move the linkage on the spline bit by bit and run it to check if its making any improvement, the eccentric screw on the clutch side i didnt mess with yet as i thought it wise to fully establish its not on the linkage side of things otherwise am making adjustments in two areas at once
i did look briefly at the eccentric screw (but now thinking about it there wasnt a lot of tension in the shift arm it would rest where it was positioned, wondering now if the arm tension spring is located correctly or possibly requires replacing
i did find this video just now and the final comment/solution  was it was fine once warmed up in the end

You may have the thought process backwards from the way I would approach it. 

If you do not have the claw centered on the drum pins, it's a complete waste of time to mess with repositioning the linkage on the splines on the left side.  When you get the eccentric adjustment correct, then you can line up the linkage on the left side.  If you line up the linkage with the eccentric out of adjustment, then when you adjust, the spline will need to be aligned again if adjustment was off. 

If the linkage is not centering the claw on the drum when released, the "mousetrap spring" at the eccentric pin is likely not installed correctly.  Claw should spring back to center.

I'll watch later tonight but sped it through on double speed & you 'Must' move the rear wheel back & forth even an inch will do, to slot the dogs into the gear.
I can see your chain is in place in the video.
It appears ya not doing that so dogs are not locating therefore the selector drum stops with a clunk [think i was on normal speed at that point early on].
Also [minor point & i maybe wrong], but i can see a steel at the back of the cluch if i stop the vid in the right place.
Hub looks to have a built in backing so i'm thinking steel at the front.
First fiber in looks to be sitting a long way out in the basket fingers.
They look aftermarket plates so might account for visible fiber protruding above the pressure plate.
I hope MarkT will sort me out [either i'm right or wrong].
In the grand sceme of 'your changing issues'--the possible clutch issue isn't serious at all. Don't panic.

hi yes thanks have been thinking the torsion return spring on the change assy may be a culprit here
i cannot find a picture of it installed on another bike to reference against mine and the manual seems of little use here
cant get to it for a few days now but will try to upload a pic of how mine is installed, i didnt want to mess too much with the eccentric screw as it would have been set at factory and i hadn't changed anything here
it feels to me like the claw doesnt have a lot of return tension to it it just sort of sits where it was last used if that makes sense

Yes send pictures I think MarkT nailed it with the mouse trap spring on the eccentric pin

Parts diagram shows it pretty clearly.  One tang on each side of pin and they should be parallel to each other.  I always have to fiddle with it to get it right.  If tangs are not parallel, it's not right. 

www.partzilla.com/catalog/yamaha/motorcy...6/dt175c/shift-shaft

Also possible to get the spring on upside down. Tangs should be right next to the shifter and fully over the shifter alignment tang.

ok thanks clutch cover off so can get some pics and update tomorrow once clutch basket is off
from whats been said so far i have a feeling the spring is possibly the issue now
it runs and idles better than has done for a long time rewiring the stator plate has helped with that i feel
new points etc once gears sorted should be in a good place