You will need to file that "burr" off. The ball has "mushroomed" the tip !

I was afraid of that! Nothing's easy is it!

I just changed the internal spring as that was easy to do with no filing  and to see if it made any difference but still only 1 ball out of about 10 makes it to the playfield, so do you think changing external (small spring) will make any difference or should I be looking at something else?

I don't think it's the level of the playfield (but I could be wrong). I just dont kow.