Thanks Neil, much appreciated. I got a handbook and parts list off the internet though and it's not up to much, yours may be the same. Very simple machines which is their strength I guess.
My saw is pretty old probably late seventies - early eighties, Startrite were very helpfull when I emailed them the serial number to check when it was made but can't tell me as apparently many of their records were lost when they moved premises. I didn't ask them about the table.
Some of the later 352s seem to have round inserts, I just can't fathom out why there would be a recess on the underside 
