Initial test results:
I installed two new Stucchi, 1/2" connect under pressure couplings- male and female at the grapple bucket. These are ISO 16028 compatible so they should mate to any other coupling that meets the ISO standards for the flat face coupling.
I installed the couplings at the grapple side during lunch today. Before installation I tested the new couplings with each other, with the original couplings that were still on the grapple bucket and with those on the tractor and all attached and detached well with the new couplings.
When I removed the original couplings, some oil came out from the lines and I dumped out what was in the couplings. I then installed the new couplings and waited until 4:30 PM to switch buckets. The grapple sat in moderate sun and the air temp. was in the upper 80s. Even with the couple ounces of oil that was lost during the coupling installation, enough pressure had built up during the day that made attaching the female grapple coupling difficult. The difference between my 2 experiences with the original couplings vs. 2 experiences this evening with the new couplings was I was able to get the connections made with the new couplings and gave up previously with the original couplings until another day. But, the new ones were not as easy as I had hoped. I would expect that if I were to connect the bucket in the morning before the oil heats up, that with the new connectors, the mating sequence should go easier. With the original couplings I still had a very difficult time making the connections, even in the morning when it was cool.
When connecting the originals, the pressure buildup was enough that I could not mate the grapple female coupling to the tractor's male coupling at all. The male plug would not enter the female coupling the slightest little bit. With the new couplings, I can push the female about 90% of the way and that last 10% is very difficult. And when the pressure is finally released and I am able to slide that last 10% and make a complete connection, a tiny bit of oil is ejected from the coupling.
I am fairly certain that last 10% of pressure could more easily be accomplished by a younger person, as my strength is not what it once was. I feel these connections are worth the $135 delivered price. But due to my individual circumstances, I may also use the original couplings and rig up connections in a bucket or at the end of a PVC pipe to store the grapple connections at when disconnected to ensure I have no future problems.
If anything changes in the near future, I will post those.