I didn't even notice those scratches on the end of the big spool until you pointed it out, but they are so small that they are only visible with the Flash on the camera, or if I tilt the spool sideways in the direct sunlight. There are no lengthwise scratches in the cylinder of the big spool but there are what appears to be just machine sideways scratches. The big spool does not have any free play end-to-end when the cover nut is in place, but it can spin around, and I can spin it with my fingers.
When I swapped the hydraulic motors 2 the opposite sides, it made no difference. The same driving Wheels acted the same way, which is why I started to look at this valve manifold block assembly. I might be able to switch the big hoses from the wheel Motors to the manifold block and see what that does, but I might have to get some longer hoses and extra 90 degree adapters.
There are lots of small passages within the block approximately 1/16 of an inch in diameter.
So far I have also been unable to remove the Allen screws in the side of the block even with an impactor, which you previously said you thought were for testing ports.
3 degrees is the low speed spec angle of the swash plate lever and 18 degrees was the high speed angle according to the specs, and that also looked visibly correct. I did not measure it. But I confirmed that the lever did move the swashplate when I had the hydraulic motors completely disassembled. At three degrees, both of the driving Wheels would stop turning after moving the machine several inches in either direction. And at 18 degrees, only the left wheel would stop turning, and the right wheel continue to turn and spin even though it was not getting traction.
I'm wondering if I just took all of these spools and ball valves out of the valve manifold block if that would get equal volume and pressure to both Motors while disengaging the brakes at the same time?