So I always thought my suspension just wasn't the best from all the complaints I've heard about an. I did a nice overhaul this weekend. And changed my front fork oil. man what a difference. I gained compression and I had no rebound before and got it all back.. So I jump on going to adjust my chain with my weight [only 155lbs] and noticed my rear shock doesn't move.. not even 5mm. nothing.. any cheapish way to fix besides buying a new shock

 

Search on hear on how to set your suspension sag.

Easy if you have someone to help!

 

Is the pre-load at it's max? If so that would be a start. Haven't ever heard of a shock freezing up. Anything is possible I suppose. Beyond that there isn't much else that can be done to improve the stock POS rear shock.
My advice is to save your money, and get an aftermarket unit. One of the best changes you can make to a SH for dollars spent.

 

check your linkage bearings are ok, they dont have much grease from the factory.

 

I agree with fabiostar's comment. Start by disassembling and checking the linkage bearings.