The stem clamp on my Birdy is not tight enough, so that the stem can move a small amount back and forward. [The movement is maybe 3-4 mm at the handlebar.]

The user guide I have here says that if the clamp needs adjustment, I have to take it to a dealer.

Does anyone know if I can do it myself?

Also, there are 2 small Allen screws in the clamp — one of them is quite a lot higher than the other one. Is this normal? [See pic].

Thanks for any info.