CAT D4D track tensioner stuck / broke spring?

Hi everyone!
I noticed that the track adjuster on my D4D doesn’t take any grease so I wanted to replace it. 
Unfortunately, the cylinder is as stuck as it can be. I tried a small porta power… no success. Sledge hammer… didn’t move. 

I believe it’s bend and hence „stuck“ in the pilot assembly. When I removed the cover, I noticed that the end of the spring is broken. I found an around 5“ long „end piece“ of the spring. The nut from the bolt (part 6H7759) also came off. Literally found it in the next to the bolt. 

Question 1: Should I replace the whole assembly including the spring or is the spring still somewhat functional? 

Question 2: How would one remove the cylinder? 20T porta power? 

Thank you for your help. Pictures attached.