Hi and Thanks in advance for all help/advice.

I replaced a rear shock on my bike. When first installed it was eye to eye 6.5" (165mm) after a 1 hour ride, I noticed the shock was a good bit shorter and I had to physically pull it back out by holding the rear tire down with my knee and pulling on the seat. I checked sag before riding and it seemed ok. I assumed it was under pressurized because I hadn't pumped it up for some time (had been working on it a while) I added air when I returned home and now the shock is only eye to eye 160mm.

Shock is cheap, but hey, I got 3 daughters!
2010 RST Element LO ( I know, RST...)

You have the lockout lever positioned all the way to the "open" position?

Yeah, it's open. It will depress fine, it just won't rebound. I have to physically pull it to make it return to full length.

Valving is defective. Contact who you bought it from or RST and request a repair/replacement.

Thanks...