I don't know anything about the 3rd function kit- other than it was an option I didn't get.
Update on my 75A- Dealer adjusted clutch. They said it didn't appear that anything was wrong with it, or broken. Seems weird that with only 175 or so hours it would need it, unless something was loose and allowed it to loosen up.
Brake leak was a small "manifold" where the brake lines split to go to each wheel. This manifold also has a couple of extra outlets that were capped and blanked off. One of these capped off outlets was leaking. They replaced the cap and checked everything out.
Other news- that I hadn't noticed- they said the water pump was making a noise, and that typically this new of a water pump being noisy, it would fail early, so they replaced that too under warranty.
Good experience, and I'm tickled in the current market I didn't have the tractor down for an extended time waiting on any parts.