To follow this up, i decided to take another power driver board over. Checked the switch in shooter lane, and all good. Fired it up and it works perfectly. So i am suspecting that U4 or U5 which control the TIPs has been destroyed. Although i'm still scratching my head why it worked in Dr Who - and it does use the same Q58 transistor for one of the slings... Anyway, i left the working board with him and will hopefully repair this one soon
