Rhodes Chroma Polaris

Hi,

I have 3 Chroma polaris synths, one has never been used (Bought for a spare in 1986) I keep it in is flight case and change the battries once a year.
just changed them and when I turned the polaris on the lights just freeze and i cant change any buttons? 
I seem to remember this may be a power supply reglulator problem, as I think this polaris was imported to the uk for the the states

Any Idea's

Peter