Speaking from the experience of being elbow deep in a couple of these KCS47 chassis, I actually shuddered when I saw the model number stamped into the back of your chassis
But, since your set is this far along, it obviously didn't have any of the horrible repair work that was done to some of these at different points in the 1950s.
Now, my advice is this. As tempting as it may be, don't run this set any more until it's gone through. These KCS47's were one of RCA's most unreliable black and white chassis of the era. The fact that it's producing a raster is evidence that it was either well cared for, or used very little.
At the very very least, the tubes have to be checked, and all capacitors need replacement. Though you're getting a raster, these sets were designed to operate with a pretty wide tolerance and still get a picture. You could have shorted or open components or tubes in the chassis, and if you run this set hoping it'll straighten out on its own, it won't, and something *will* smoke or burn out.
If you're not keen on tackling the job yourself, tell us where you're located....I'm sure one of us would be glad to give you a hand