no help to ya...the old chain trencher i have... is so old. that it is a bit scary. and found in going through a rock driveway, and then into some very dry clay. i had to soften things up with some water (letting things soak for a few hours) and then going back at it. a good tight chain works better, than a loose chain. though if you make chain to tight, the linkages begin to stretch, and it makes it that much harder for engine to turn the chain (i want as much power as i can get to chain digging through the ground). to loose of a chain. and the chain begins to hit bottom side and top side of the bar for the chain. and just makes a mess. both destroying chain, and fighting machine to dig (much slower digging).
for the old trencher i have. i ended up using some old transmission oil / engine oil. and giving a slight drip of it across the chain as needed. the old oil seemed to work better vs regular grease. due to regular grease was just working itself right into dirt and getting lost in the dirt fairly quickly and never got a chance to work itself into the pins of the chain. a little drip of the old oil. seemed to drastically reduce friction and keep things moving fast and smoothly. and did not collect dirt / dust as much. granted oil = death to plants and grass and EPA like regulations for pollution. and the old oil made a mess of things come clean up time of the trencher.. but for this old trencher i have it was a huge difference.... modern trenching machines not a clue.
to note it. i had to keep re-adjusting tension on this old machine. (long screw with 2 nuts) to lock in the tension. the vibrations and abuse i was giving it, kept moving the nuts and in that reducing the tension of the chain. (bad design, and/or very old machine / or just plain abusing it take your pick )
