Hard to believe it been almost a year since the last time I was on here. Time does fly...
Unfortunately I have no words of wisdom for the recent subjects, just some memories. Back in 1968, on the 680, 685, 690, 695's, we used ti have problems with the swing gear box loosening up. If I remember it was supposed to be torqued daily. We tried adding adjustable stops that were basically large screws that were tightened against the part of the swing gear box housing where the hydraulic motor mounted. These also had to be tightened often as they would eventually wear into the gear box housing. One of our distributors came up with an added on bracket that served as a clamp on both sides and the top of the gear box. It wasn't in the territory I worked and I never saw one but it was reportedly about the best repair up to that point.
Those control rods look familiar. I'm sitting here moving my feet back and forth trying to remember how the various levers and pedals were arranged back then. I seem to recall the right lever was for the swing then. Reason I recall that was one of the more popular modifications we were doing was top convert them to left hand swing. As there was that counter shaft behind the main shaft for lever mounting, one could set the controls up just about anyway one wanted.