replacing wall mounted bath mixer taps

[wetsleet]

I am replacing a wall mounted bath mixer tap (not thermostatic) with new. The trouble is the centres on the new tap are a few mm different to the existing, which was fitted onto eccentric reducers.
It seems to me that the eccentric reducers are the bits which need to be adjusted to line up with the centres of the new mixer.
Two questions:
how do I get a grip on the exposed end of the eccentric reducers in order to adjust them?
how do I get the eccentric reducers tight again - I assume if they are not tight I will get a leak, I assume if I tighten them up then they will return to their original spacing between centres?

 

[WHPES]

You could try and grip them with pump pliers - take care not to damage the face. There's always the risk they will leak but try to adjust them by turning clockwise as opposed to undoing.

 

[REDSAW]

trial and error, use a 12mm spanner on neck and dont overtighten.
hand tight nearly good enough.