Hi Dave

sent a PM as luke gave me a call and thinks he knows the problem

Thanks Jady . Earlier today I found that there is no power to the Optos .
I had decided to contact Luke to see if would help me out . I wonder why he rang you and not me ??

Anyway, just called and left him a VM.

Fault is not that simple though , because there is no continuity in the harness between the plug he is talking about (connects to J118 on power driver board) and the plug connected to J1 on the Opto board (according to the manual there should be as this is where the Opto board gets its +12V and earth (pin 2 and 3 on the connector plugged into  J118) . That same plug (J118) has the piggyback connection for the 12V to the topper.

Before I checked the harness I checked related fuses (F115 and F116)