I feel your pain....was in this same thing only 5 months ago. Google concrete delamination and there is lots of information on this condition. Some of the hollow spots I had I was able to dig all the way through with my hands. Long story short I finally got them to remove some of the loose...
I inherited this Quincy 308 air compressor and was told it would not work. I wired it up and to my surprise it started pumping air. It had a couple of pipes broken off in the tank so initially I could not really tell what it was doing. I got the broken pipes out and I decide to pull the head...
Here are some closeup pics that I hope show the detail you are looking for. Modifications to the slack adjuster are that I pushed the sleeve in that goes around the adjuster nut and welded it in place. I didn't want to have to push it in every time. Then I cut a slot in the slack adjuster so...
Someone mentioned using a slack adjuster from a big rig brake system. Here is some pics of the one I have requires very little effort to turn and you can stop wherever you want.