An incorrect mica insulator was supplied. The supplied washer measured 25 by 20 mm and had one 3 mm hole 7 mm down from the 22 mm edge.
I was able to modify it by punching cut outs on each edge to accommodate the fixing bolts.
Also I thought the connector pins were a too easy fit in the pcb holes.
When one turned the board over to solder them they fell out.