Unloader Valve or Control Valve?

[Bob in Tennessee]

I described in an earlier post that my lift arms were stuck in the top position on my Ford 841 even with a great deal of weight on the arms. I assumed it was mechanical because there was no leak down and when I removed the lift cover, this is what I found. After removing the cylinder, the rocker shaft moved freely and the piston easily blew out with compressed air. This has left me greatly confused. Which of the valves controls the release of pressure? Also, is it possible to replace the valves without special tools?
Thanks
Bob

 

[Btzj02]

Take a look at this video.

This guy does a great job showing how to access the valves on a 960, which I assume is similar to your 841.

 

[Bob in Tennessee]

Thank you great video!