Trouble digging in with my 40C

[JD40c]

I spent two evenings pulling three diseased apple trees out of our front yard. My 40C (with #76 blade) really had a hell of a time cutting through the sod and top layer of soil. Once I got through that, it'd start rolling soil out nicely.

I'm not sure what normal digging capabilities should be with this crawler. The pivot pin for the blade itself is pretty worn and I think the blade rolls down a little so the cutter bar is at a more blunt angle than it should be. When set down on a hard surface, should the top and bottom lead edges of the blade be vertical if you drew an imaginary line across them? Or should the lower cutter bar jut out a little farther? Can you still buy a replacement cutter bar for a reasonable price?

What steel would make a good replacement pivot pin? I'm going to machine new pivot bosses for the blade but the old pin is worn and bent. Something along the lines of an A36 steel?

[Lavoy]

Seems to me that the moldboard itself is fairly vertical. The cutting edge lays back a little bit, but with a curved cutting edge, it does not have to be much. If the moldboard is rolling forward as you dig, that will hurt your digging capability. New cutting edges for that blade are cheap and readily available. Go to an industrial supplier and ask for 1/2" X 6" X 6' grader blade. Most good parts guys will just say half by six by six, and go grab you one. Last ones I got here were under $30 each.
As far as pivot pin, I use a 1" grade 5 bolt. I either weld a short piece of bushing stock, or cut out and put a heavier piece of plate on the moldboard where the blade pivots. Originally it is only about 1/2" stuff.
One of the other critical things is the angling braces. Sometimes people just drip a pin in them and go. This is incorrect, they are supposed to be bolted tightly every time, as they add strength to the moldboard both top to bottom, and left to right.
If you put in a new pivot pin, maybe fix the pivot points a little bit, and make sure your angling braves are good and tight, and put on a new cutting edge, you won't bel;ieve the difference.
Lavoy