Technical Shock absorber compression and return

When shock absorbers are off the car and then closed to full compression should they stay in that position or return to full or partial extension. My new rears return to full extension but checking my fronts(So Cal on a mono leaf) they stay compressed. When they are on the car and I move the suspension up and down they compress and then return but I am wondering if they have lost a bit of their efficiency.

 

So-Cal sells a nitrogen charged shock and if they are functional they will go to extension

 

Older "hydraulic" shocks were not gas charged. They were designed to work and dampen suspension movement but did not self extend. They can be good or bad, but they don't self extend. There should be resistance to movement when you try to I'll on them or compress them rapidly. No resistance = bad shock.

Later, gas charged shocks were pioneered by Bilstein ( I think). Since then most all new shocks are gas charged and they will self extend. If they don't, they are bad.