I ran the 500 this morning and all seemed to be running as normal.
Top temp at 79.5 or there abouts and bottom temp about 57
Normally I will get between 3.5 and 4 litre @ 93% and during the last 500ml the top temp will start to climb.
Today however, at the 3 litre mark the top temp dropped so I raised the bottom temp, this started the top temp to jump and I got a massive surge of output.
I couldnt control the temps from there on so I gave up.
The only thing that I changed was to add a small amount of copper mesh to stop the saddles dropping out and to fill the 1 inch gap in the column.
Could the mesh have caused this???