:welcome:
I'm sure metric, but recall using an sae socket on them.
Measure across the nut but seems if my short memory is even close, it was 1 1/2 socket in a 3/4 set using the long extension and breaker with a pipe for some extra leverage.
What I do is sharpen them in place with an angle grinder. Just pick up my 513 with the FEL and stand it on its edge. Work standing up. Might get some oil from the gearbox vent but put down a rag if concerned.
edit: socket size, as the manual says 1 1/2 " and tighten to 433 lb-ft torque