Hello All
Joined the forum just so I could let you know about my experience with the same issue. Apologies for the long story.
I bought a brand new 4044M with backhoe early summer 2017. I bought it from a large JD dealership in Eastern IA. After delivering the tractor to my house, the salesman demonstrated how to remove the BH - it was evident that he wasn't very familiar with it which made me start to pucker because I feared he would unhook the power beyond lines since he left the engine running. As I'm thinking this, I see him reaching for the couplers (it was like one of those slow motion scenes in a movie where the guy is saying "NOOOOOOOOOOOOOOOOOO" in a 'slow motioney' kind of way). I couldn't get it out quick enough and he ended up unhooking them. Immediately the hyd. pump started making noise and I said "I don't think you're supposed to do that while the engine is running". He was pretty flustered and told me to "turn if off, turn it off". This is an important part of the story because it set in everyone's mind that this is what caused all of the following hyd. issues I had with this tractor(s). He assured me it was "ok" and nothing to worry about. I said "I don't think so" but will run it this weekend to make sure.
That weekend I moved around 5 FEL buckets of gravel and noticed hyd. fluid almost pouring out of the hyd. pump. In addition to this I heard and felt the 'barking' that you guys have been talking about in the loader. I called the dealership and they sent a mechanic out. I told him what the salesman did a few days earlier and the mechanic just dropped his head and started shaking it. He jumped on the tractor and started lifting gravel with the loader. He could hear/feel the barking as well. He tested the BH and said it was even worse. They took it to their shop after being in my possession 5 days. They replaced the pump but couldn't get rid of the barking/jerking issue in the loader and BH. They called JD engineering (forget the name - Deere Tech??) and said that by unhooking the power beyond lines, he likely blew every seal in the entire hyd. system but Deere Tech wanted to think about it a while.
A week went by and I heard nothing from them and the dealership said they heard nothing from Deere Tech. I needed the tractor so I made them bring it back while we waited so I could at least get my projects done. A few more weeks went by and still nothing. This got us calling JD directly as well as the dealership regional managers. They offered to get me another 4044M, which I agreed to since we all still thought this was due to the power beyond lines being unhooked. They had one shipped in from another state and put my BH on it. It was still a 2017 model but an early one and had clearly been sitting out in the sun all year because all the black plastic was faded bad. It also had a visible coolant leak with only 4 hours on it.
I used it the following weekend and it did the exact same barking/jerking thing with the loader that the first tractor did. The higher the RPM, the worse the jerking would be. This got me researching on the internet where I found you guys. What you described is exactly what I was experiencing. I called the dealership maint. manager and told him about what you guys found out and even provided the part number for the new loader valve as well as the link to this forum thread. They didn't act like they wanted to hear any of it. A few minutes later, the salesman I was dealing with called me and said "I'm coming over right now to get to the bottom of this".
Once he got to my house, he wanted me to show him what I was talking about and thankfully, right in front of him, the loader had the worst barking/jerking fit I'd seen so far. He couldn't deny it. I said, "I provided some good info. about how to fix this, will you be able to do it?" It was clear he had no interest in doing anything to fix the problem so I said "I want a divorce - take it back". He said "No problem, I'll have a truck over in an hour to get it and we'll get your money back". And that was that. The dealership did end up getting all of our money back and I was out of a tractor - which totally screwed up my entire summer project.
I ended up buying a new Kubota MX4800 with BH which didn't show up until after summer was over. This experience had its own issues that I'm still not happy about and will post on it later if anyone is interested.
After owning it a couple of months and being able to compare it to the JD 4044M, I would still prefer to have the JD back. This isn't due to any brand loyalty, just based on operational experience, refinement and personal taste. It's an absolute shame that JD would let something like this happen. I wish I could take the things that Kubota does better and the things that JD does better and have a hybrid built.