Namiki

Hi, I need a bit of advise
I have a collection of 5 montblancs all are excellent writers never had any problems , I tend to go for the limited editions with montblanc.
About 6 months ago I purchased a Namiki ( nippon art crane&turtle)
Now this pen has a fine nib which I find a bit scratchy , I thought it may get better as I use it but there has been no improvement at all.
seconly the piston to does not fill up , it just fills to quarter and stops .
To be very honest I am not too happy with the writing quality of this pen , the work on the barrel is beautiful but overall I dont get the joy of writing with this as much as I enjoy my other pens, also I have never had a problem with any of my MB.
I would appriciate if some one can tell me if they have experienced similar problems , or have I just pulled the short straw.
regds
Farhad