Reply to Cat power:
Thanks for the advice john. I think my track plates are the standard width for the d46u and grouser hight is about 25-30mm so I would say they are about halfway from new. The tracks don't look to worn out in fact I think they have been done up not long ago because they do have outer drive rings welded to the old drive sprockets but I will keep an eye on them
As said check the jockey spring retaining u bolts and main bolts to the crankcase, and the main spring especially the main spring retainers located on the track frames as these often wear very thin and can crack. There are bolts through these brackets with a roller arrangement which is often worn out, missing or botched with some other bit of steel. The end of the main spring can be worn very thin and can bust off under load.
There is in actuality little to stop the front flipping up and over the back if working on steep slopes if one side or the other fails at any point where the main spring attaches to the track frame or the jockey spring attaches to the engine casing. A really shabby system in my view and one that I reinforced at all points with my D4 7U, as well as fitting a heavy ROPS. Even so I never felt comfortable when pushing dirt up steep slopes, eg., dam face. But I am easily scared by machinery😊
On my D7 the end spring retainers have been modified to enclose the main spring in a pocket so it cannot lift up and away from the track frame and there are heavy hoops fitted around the main spring under the engine/transmission casings to prevent these parting. The 7 was used for logging and is fitted with a huge winch. Clearly they did not want the front coming up and over when working on steep slopes even tho this is unlikely with a cable blade!