The clutches do have springs that hold the disks in engagement - about eight springs arranged around a hub. One guess is that the disks are hung up on a ridge worn into one or both of the hubs. It's a medium size job to refurbish the steering clutches. Parts are available. The main criterion for dozer value is the undercarriage condition. You can determine it by taking various measurements. The easiest way is with a gauge designed for the D6 which is just a flat piece of plate with various cutout that when place against the item to be evaluated, shows the 0 and 100% worn sizes - 100% worn is economically worn out. The other way is to measure to a precision of about 1/8" in order to get a good estimate of the size. There's a diagram on this forum somewhere that shows the measurements to take (someone will chime in with where to find it) and the typical parts measured are: idler profile, roller profile, sprocket tooth wear, and rail height from the grouser plate, and the grouser height itself. A diagram also exists on how to drill the holes required to fit an electric starter for the main engine.

Oh ok, I forgot about that. Yes, perhaps the lever inside it is hanging up. You can look in the serviceman's reference for instructions on how to dismantle it. If is is hung up, careful that it doesn't pinch your fingers when it lets go