I am in the course of a light overhaul on an origional Lister 6/1. Since I had one flywheel off and the gib key loose on the other, I wanted to replace the felt crankshaft seals. If you do one at a time you do not have to fight with the crankshaft or gears.
You do have to get the oil lines out of the way for the bearing housing to slide off the crankshaft. To do this you have to remove the pipes from inside the engine. My book did not show this clearly and my search here was inconclusive so after a visit by my Amish expert he showed me the trick.
Here are the parts:
The connecting pipe will slide out. Remove the outside fitting, slide the connecting pipe out thru the inlet, then the two feed pipes to the bearing oil cups can be easilly removed.
My feed pipe was stuck. Before I forced anything, I asked and discovered the trick. I hope that this helps someone else.
Bob