[seanjamesterryb]

I've just found a blown resistor on the middle board, it is next to the left heatsink. I can't read the colours as its too burnt. When I desoldered it, it broke in half. It looks like a 10 ohm 1/2 watt resistor. I will change that and put new sleeves on the transistor pins as they look short. They might have shrunk over the years. I have put the two old transistors back in.

Thanks for all your replies.