I think I may have blown the LEDs
they are labelled as RS 306-061 but no longer supplied by RS an I couldn't find a Datasheet

If it has 10v input I reckoned it would be safe if tried it with a 5v supply but saw no signs of light .
Tried with a 12 v I saw a single tiny flash then no more .
Then I found this data sheet https://www.silicon-ark.co.uk/datash...-datasheet.pdf
I am suspecting I may have zapped it with too much reverse voltage. could that be ??

Where to I go for replacements ? Can I select ones which would be oK with the voltages I have available , ie 12 v or 5 v