I am also only familiar with a 3-wire voltage regulator on 8Ns. Perhaps the 4th wire grounds it? That said, you really need to know which terminal is which because you can immediately ruin the regulator if you touch a jumper wire to the wrong terminal. You usually take a short wire and just...
You can make sweeping turns with ground-engaging implements, but sharp turns with the implement in the ground will break things on Ford Ns. Ford beefed up the upper lift arms with my model but I still lift plows, cultivators and disc harrows when making turns.
I'm not familiar with the term "third function" but, when I bought my MF-1533 new in 2006 I had the dealer install remote hydraulics so that I could operate my hydraulic toplink. Hope this helps some.
As John suggested, start with the top cover and check the piston. The factory piston had 3 steel rings. Rather than a ring job on it, I would replace it with a piston from the '53-54 NAA with an o-ring and leather backup washer. It will seal better. Also take a hard look at the cam follower...
Sure it is. 8N hydraulics, when working properly, can lift ~800 pounds and it will lift all three implements you listed above. Parts are easy to get and how-to information is available at some websites and on YouTube.
Yep. You can learn all you want to know from this compilation of photos and restoration info in this document: https://www.ntractorclub.com/manuals/tractors/An Introduction to the Ford Tractor 2N Warhorse, v06-09-16.pdf
The 960 44043 is what is throwing me. The 960 would indicate that the motor came from an earlier Ford. This is what a model and serial # would look like on a 4000:
In addition to the ballast resistor? If so, this is probably your problem. An additional inline resistor to the coil is only needed when you have converted to 12v but retained the 6v coil.