I was using my Allis Chalmers HD-4 crawler the other day when the right steering clutch lever suddenly went limp, like it wasn"t connected to anything anymore. It had been working fine before so I thought that a clevis pin or something had fallen out of the clutch linkage. But I can see nothing externally wrong so I guess that whatever happened must be inside the clutch/brake casing. Which of course is a real pita to inspect since the hydraulic reservoir sits on top of it as well as all of the hydraulic controls.
So what do you think might have "let go"? Two years ago I replaced the clutch and brake on the left side and that was no fun at all.