looking at this how To from Jules
https://the75andztclub.co.uk/forum/s...ad.php?t=54384
and looking at Rimmers web site
https://rimmerbros.com/Item--i-GRID001740
https://rimmerbros.com/Item--i-GRID001722
even just changing this seal or housing gasket looks to be a big task. Haynes manual suggests a thermostat that has done 5 years may well be past its best.
perhaps I should change pump, thermostat and gasket and the O ring so I only have this job to do once.
macafee2