odd headlamp issue

[slammed 66]

Hey fellas,

Ive just bought my second silvia this month and this one is to be my every day smoker.

First issue ive found with it relates to the high beam. If i flick it on the lights dim to sidelights only. Dipped beam works fine and so do sides but not mains.
Any ideas what the likely culprit could be?

Many thanks

Ross

p.s. pics of the car to follow