I measured the thread length as 20mm so I wanted to move the collars so I would have about 15mm showing. I tried the blunt screwdriver with thick electrical tape as well as punch method but it seems like it wants to tear the soft collars all to pieces. Do you guys have a method of turning these things without notching them all up? I can't see a spanner wrench fitting in there because it sits quite low in the swing arm. If the wrench was offset then maybe. There must be a better way. If there was one area they should have used a few more grams of weight they should have used it here and made the lower collar out of steel. I've seen all the available wrenches and to be honest I can't see them fitting in there to be of any good. Any suggestions appreciated.