Ok quick update. I satin the shed for a few hours this afternoon, had a beer and cleaned everything thoroughly. Installed new seals and put pistons back into place. I now have the calipers back on the bike now, just need torqueing up. I gave the problem helicoil one final try and managed to get the insert flush one side then tidied up the back end so that was flush too. Probably would have been easier if I had used the correct length insert but I think it will do for now. Here is my next issue though, I filled the brake fluid reservoir and started to pump the lever but it just pumps endlessly, there is no pressure to push the pistons out. Does that mean it needs bleeding> which side do I bleed first? oh and how exactly do you bleed the system? Thanks for all the help so far.....