I sorted it myself. not a lot of help from so called lawn mower mechanics. phoned around ,no one new much at all. still waiting on 2nd reply from Husqvarna. BUT I had a go at a few mods while waiting. I first ground down the edges of the 'spacer' then using long bolt ,nuts and washers and sockets.Used them to compress the fan onto the spacer. This must have come originally as one complete unit, not two items. Anyhow that worked nice tight fit. Then there is another plastic spacer that fits into the fan that the blade attaches to. This had to be filed down inside as it has a circular centerpiece that fits into a hole. The hole was undersized. Hopefully get it back together and get it working.
This is the plastic blade spacer.