Re bobbins, yes, we have made (Sand Cast Aluminium) heaps of these, not sure if I have any in stock at the moment, will have a look tomorrow.
The original bobbins are a unique shape to handle the loads they were designed to take, and to make sure they stay put when bonded in correctly, a round, or hex shape bobbin could eventually come loose.
I have removed several damaged bobbins from the S2 body and replaced with new sand cast aluminium bobbins, and never and any problems with them.
The original die cast bobbins are made of pot metal, which is a zinc based alloy, it is basically a crap metal, and it cant be welded.
A bit of an article about bobbins here at our blog.
http://elantrikbits.com/lotus-elan-blog ... place-job/Col.