semaphores

Hi All,
I was looking through my collection of semaphores on the weekend as I someone asked if I had a set and I was looking carefully at them and noticed the set off my Jan54 are actually different to some of the later model 55,56,57,58 sets. It is to do with the spring system on the back of them. Anyone else noticed this?
T54

yeah noticed that on my 54 a few years back when i was trying to source a good second hand working set back in the uk .
the knacked ones that came off the car were slightly different in mechanism to the ones that went back on,which i sourced from sweden in the end.

and the lenses are a different colour also:thumb